I was looking for a 'Maybe... Depends on implementation' option but then I realized the only two where 'yes' and 'no'. I said yes, simply because the IRC during the Ludum Dare compo has a great feel (any LD competitors, you know what I mean, sleep deprived coding and helping each other out on there - a real sense of community) so during compos or other events based on a fast(er) timescale, a live chat would be great - but while IRC is great, pretty much anyone can log on including spammers etc, flash is just, well, horrendous but AJAX sounds good or a regulated IRC would be perfect IMHO.

Just my two cents.