Heh, as if they're a rare caged animal, confined in front of a microphone for any curious passer-by to talk to at a whim.
Mostly GMs are like people. The way you talk to people online is through things like skype.
ICC is known for having GMs, but if you want to talk about chess, first they'll want to talk about money (their instructor's fee).
Does anybody know a website where you can talk live with gms?