Last night I played in a session of Apocalypse World GM'ed by Charles Jaimet (who's working on an excellent gaming interface for G+ Hangout). It was certainly a wee bit intimidating to be in a group containing Greg Christopher(Chubby Funster), Tavis Allison (ACKS) and Peter Adkison (GenCon, former owner of WotC). I just tried to hold my own ;)
It was one of the best roleplaying experiences I can recall being a part of. Obviously the group of players involved was a major part of that, but I must admit, the system was too.
Apocalypse World pretty much forces your to role-play, but in such a natural manner you hardly even realize it.
I stand behind my earlier comments about the presentation and writing of AW - it is so hard to work your way through the rules that I had to put them down multiple through sheer frustration. Someone needs to do a rewrite to make it user friendly. Still, as many told me earlier, it plays so much better than it reads. I stand partially corrected ;)