I have to apologize for the lack of posts here this month. Hopefully the all of the other amazing hunter blogs out there have kept you sated with hunter reading. I've been working on getting things ready for 6.1, which launched yesterday to give us some substantial changes to hunters.
The great news is, before considering the tier 17 set bonuses, all three hunter specs are dead even for single target DPS. In AoE there's some slights parity, with MM falling a bit behind, but in general, this is the closest we've ever seen the hunter specs.
With the tier bonuses, however, we have a new raiding champion spec in Beast Mastery, which will be providing the greatest Single Target and AoE DPS. I can't say I'm super excited about having spent the last couple months trying to get as much Multistrike gear as possible, only to have to start switching it out. And after a whole expansion where BM was on top in MoP, I was enjoying playing SV and MM a lot more. I suppose I should be glad that all of the hunter specs are at least viable, though, so I'll try not to complain about BM too much.
My guides (which is what I've been spending most of my time researching) are now updated for each spec, over at the Warcraft Hunters Union.
Beast Mastery received the most attention in 6.1, with Focus Fire's buff, so consequently, it's the most changed of guides, but MM is a little bit different now, too. For any other particulars your curious about, check out all the WHU hunter guides here.