Here's the reports I've gleaned from websites, assistants, news reports and radio DJ's. This is all speculation, so don't think I'm announcing anything official and I am in no way affiliated with the fine people at Goldenvoice.
The Police (despite the presale password being a joke, they're looking for a place to perform and Bonnaroo is out)
Gwen Stefani (I shudder, but her tour dates are open)
Smashing Pumpkins (Billy keeps hinting at a reunion around this time, despite the fact it seems James Iha and D'arcy are refusing.)
David Bowie (Just because he's wanted to, but a longshot)
Modest Mouse (As they speculated that they were going to be there this year anyways.)
The Dresden Dolls (Okay, I have nothing to support this, but they are on my wish list.)
Muse (They're open, but will they show up?)
Lady Sovereign (Widely rumored)
Queens of the Stone Age (Also said they may play, but that was awhile back)
The Killers (Coming off a world tour, they may want a break. And the month break they'd have might kill their momentum.)
Incubus (Same deal as The Killers)
Fat Boy Slim (Spending some time in Brazil beforehand, may not want to head right back out)
The Knife (One of the members is pregnant, so highly unlikely)
Daft Punk (Have no desire to return to the U.S.)
Neil Young (I would love to have him play, but I don't think he's even considered it.)
Bright Eyes (Air is already on the schedule. Add Bright Eyes and people will fall asleep all over the place)
Justin Timberlake (He's in England on those dates)
Pearl Jam (Flying back from London to New York on their way to Toronto. Don't expect a stop off in the desert.)
+44/Angels & Airwaves (Travis Barker is injured, the others aren't around)
Morrissey/The Smiths (I hate to constantly dispel this rumor, but last year was the last chance. Marr and Rourke performed in 2005, but Morrissey continues to refuse, and even turned down 5 million last year to reunite. Will he make it up this year? More than unlikely.)
And finally, the rumors to really set your minds a-spinning:
Prodigy (playing in the desert a month earlier and ready to hit the desert again.)
Moby (eager to get out and get a chance to speak in front of 100,000+)
Celine Dion (got you!)
PLEASE note that the organizer for Coachella announced this morning on KROQ (Los Angeles - 106.7FM) that there will be LESS BANDS EACH DAY so very few will be added as surprises, though that one certainly will.
Also keep in mind the powerful activism roots behind Ozomatli, Manu Chao and RATM. So bands like Mana may show up as well, but take that with a grain of salt.
That's my report, hope it helps.