Might be a tad early for 2012 long shots, but some of the Euro followers might make a guess. It would be nice to have Mango, Byers, and Ruiz take home some hardware, but they need to work on par terre defense. And make the team. Predictions for Worlds in '11 might be easier. The thing I've noticed is that while you can expect some dominant guys to be on the podium in '12, guys like Lopez from Cuba, and Albiev from Russia, all the others, and those you haven't heard of, come out of the woodwork for the Olympics. Look at Andrea Minguzzi from ITA, he came completely out of the woodwork, but then, he was involved in that fiasco with Abrahamian (the one who threw his bronze medal).
So much comes down to your draw, how you feel that day, and a bunch of luck, like calls going your way. If you go back to Cejudo's gold, he got a great draw (the top guy was knocked off by a headlock in the upper bracket), wrestled very well, got some seriously good calls (eg, 3-1 when it could have been 2-2), one of his opponents stopped wrestling at the edge of the mat (he gutted the guy), etc. All the pieces came together for him and he didn't squander them. You have to be prepared to win.
So, while fun, it's hard to pick the favorites, let alone the longshots.
All that said, while I don't know the field that well, I like these guys:
55kg It will be interesting to see if Soryan can hold this weight. I've heard he makes a big cut to 55 and I believe it (he's really really tall for 55kg). The Korean looked good in Moscow getting silver. Mankiev will not go down easily. Mango can throw, but needs to execute faster.
60kg Albiev, when healthy, is a monster. The KOR and JPN wrestlers impressed me at this weight.
66kg Vachadze looked good at Worlds, lots of guys in the hunt here.
74kg Cebi from TUR looked very good. There's a young RUS here (Sharafetdinov) that would be ready by London. Pretty wide open weight. Marc O Madsen is good and beat Cebi last year at Worlds. He's a choker (he chokes people), scroll half way down this page, he's in blue: http://tech-fall.com/2009INT/09Worlds56.html
84kg This will be fun in London. I like the Cuban. The Croatian guy would be fun to shoot celebrating (he did the worm after winning third at worlds). The TUR should be on the podium.
96kg Aliakbari (IRI) could win gold in London and has to be the favorite after Moscow. Khustov keeps getting beat at this weight. The SWE (Lindberg) is HUGE! Ruiz was in the mix.
Photos of all these guys can be found starting here: http://www.tech-fall.com/2010INT/2010Worlds19.html
2009 start here: http://tech-fall.com/2009INT/09Worlds10.html