Which is fine – but can Marshall Bruce Mathers III, by far the biggest-selling rap artist in the world, possibly reclaim his position as the world's most famous MC? His long, self-imposed exile is the least of it. After a reconciliation with (and subsequent divorce from) perpetual ex-wife Kimberley, the murder of a close friend, rumours of creative burnout, signs of weight gain and a much-publicised "dependency on sleep-medication", he's starting to resemble, for sheer weight of troubles, the very Michael Jackson he once mocked.
At 36, even if Eminem's musical skills are intact, his road back may prove tough. Consider the following obstacles he'll have to overcome along the way...
1. That tricky back-catalogue
Any new Eminem album (the first, reportedly titled Relapse, is scheduled for release in May, to be followed by Relapse 2 later in the year) has to be substantially better than his last effort, which managed both to dent his critical reputation and weaken his commercial standing. With its lazy rhymes and flat production, Encore seemed the work of a man who'd audibly lost interest in what he was doing. "Just Lose It" and "Like Toy Soldiers" each topped the UK charts, yet as a whole the album lacked the brassy provocation and spiteful energy of his best work. Worryingly, the first track to appear from the new sessions – titled "Crack a Bottle", and featuring guest verses from perennial sidekicks Dr Dre and 50 Cent – hardly inspires hopes of a creative renaissance. It's weirdly lifeless, shoe-horning some awkward rhymes ("Ladies love us, and my posse's kickin' up dust") to a weary snare loop, with Dre seemingly on auto-pilot, and 50 Cent sounding even more uninspired than usual. Eminem himself, meanwhile, sounds almost tame. Admittedly, a track such as 2002's "Lose Yourself" set the bar high – it ranks with LL Cool J's "Mama Said Knock You Out" and Public Enemy's "Fight the Power" as one of the greatest hip-hop singles of all time. And 2000's The Marshall Mathers LP is still one of this decade's essential releases. But no one's necessarily expecting Eminem to surpass those glories – just to remind his audience why they cared in the first place.
2. Staying one rhyme ahead of the pack
In this respect, at least, Eminem may be safe. For all the effect hip-hop has had on the cultural landscape, it has yet to produce many actual stars. Indeed, it says something that two of the biggest names in the field, Tupac and Biggie, only achieved mainstream fame after (and because of) their early, violent deaths. Things haven't changed much. With over eight million albums sold, Lil Wayne (right) is arguably the most commercially successful hip-hop star on the planet right now – yet how many Heat readers could pick him out in a crowd? And frankly, who else is there to rival Eminem's stature – at least, among working MCs? Diddy has finally taken the hint, and retired. Jay-Z seems more and more a CEO who occasionally flirts with making records. Anticipated "crossover" stars such as Mos Def are still stuck in supporting film roles and middling sales. Despite a string of movies and sitcoms, Method Man never found a mainstream audience – likewise Ice Cube. And veterans such as Flavor Flav and Snoop Dogg are consigned to the grinning indignities of reality television. Kanye West is probably the closest thing to a bona fide celebrity – yet even he's never quite achieved Eminem's prestige. Maybe he's too ubiquitous – constantly blogging and Twittering, glimpsed at every fashion show, première, party – there's no mystery. Kanye leaves no room for the close identification necessary for fan-worship – a topic, incidentally, which formed the basis of Eminem's landmark 2000 single "Stan". In this respect, Eminem might have an advantage. His acting chops in 8 Mile didn't exactly make one long to see his Petruccio, but on stage, at least, he demonstrates the focused intensity and spotlight-holding charisma of a genuine star – arguably, the biggest that hip-hop has produced.
3. Always read the sell-by date
Given that it's been four-and-a-half years since Encore, Eminem might find himself the victim of something entirely beyond his control. Pop musicians today have a shorter lifespan – in commercial terms – than at any time since the "hit factory" days of the mid-1950s. And hip-hop careers are the most ephemeral of all. It's not uncommon to see one- and two-hit wonder acts such as Coolio (right) and Sisqo issuing Greatest Hits compilations after just two studio albums. They know the deal: cash in quickly, and get out. In commercial terms, even the biggest reputation doesn't mean a thing. Rakim's long-awaited solo debut, The 18th Letter, failed to sell – despite a substantial number of critics, fans and peers all citing him as rap's all-time greatest MC. Q-Tip is hardly in the same league technically, but is far more beloved, able to cruise on the accrued goodwill from those summery Tribe Called Quest cuts. Nevertheless, his recent comeback album (optimistically titled The Renaissance) hardly set the charts alike. Nor, for the matter, did the last Wu-Tang album. Even major stars today can't "do a Kate Bush": vanishing from the scene for years at a time, releasing nothing, maintaining a reclusive silence – secure in the knowledge that, when they do finally return, loyal listeners will stump up for their latest offering. It's a very different market out there in 2009. Fans' memories are shorter, their allegiances more fickle. And there are simply more choices, both within music and outside of it, to tug at their time and purse-strings. Eminem's greatest test, therefore, might be of his listeners' brand-loyalty.
4. The bootleg B-boys
Hip-hop fans love their music – but they don't much like paying for it. Look on the peer-to-peer sites for even the most second-league act and you'll be deluged with hits: album tracks, singles, guest spots, rare cuts... Free file-sharing, not dollar-down purchasing, is the primary means of distribution for most fans, a fact that artists and labels reluctantly concede. This makes some sense. Hip-hop came up out of the underground via mixtapes, semi-legal bootlegs hawked outside gigs and on the street; its commodification into a Tower Records-friendly retail package was always uneasy. Artists such as Young Jeezy, Nas and Jay-Z are at least as active on the mixtape front as they are making albums. Consequently, there's a whole strand of these performers' careers – often, including some of their finest work – that never so much as troubles the casual listener. So even if Eminem's new album is appearing on iPod playlists from Detroit to Kenya, how will we know? What are the terms by which the commentators and pundits will deem it a success? Must he equal Lil Wayne's Tha Carter III, which famously sold "a milli" in its first week? And if he doesn't – if he only shifts, say, 400,000 units in that first seven days – does this mean Game Over?
5. The Obama effectSince Barack Obama's election in November, hundreds of articles have been written debating the possibility of a "post-racial America". Whatever the merits of this contention, it's most unlikely that it cuts much ice within the hip-hop community, where a rallying black consciousness, coupled with a dose of gangsta fetishism, have long been the defining characteristics. As a white guy, Eminem's success has consistently defied conventional wisdom. Initially, his friendship with Dr Dre, combined with his undeniable mic skills, earnt him a pass. But in 2003 he found himself embroiled in controversy after the leak – and subsequent release on CD by US hip-hop magazine The Source – of a recording in which he made derogatory remarks about the African- American community. This doesn't have to spell the end – at least as many white kids as black ones constitute Eminem's audience. But does a black president (seen here with the rapper Ludacris) signify a paradigm shift, a celebration of all things African-American, and by extension, a repudiation of Marshall Mathers? Should the real Slim Shady please shut up?