Weekly development meetings are held in #dri-devel on irc.freenode.net Mondays at 2100UTC (2:00PM PDT, 5:00PM EDT). It is a general time for developers to get together and talk about current projects, make decisions faster than can occur through email, and answer each other's questions.
All developers who are interested are welcome to join.
Please note that the #dri-devel channel is not a technical support channel for end users, so XFree86 (Xserver/X.org) /DRI configuration and troubleshooting issues are off topic. The #xfree86 (#xorg ?), #dri, and possibly #nvidia or #ati channels are more suited to those types of discussions.
Logs of all developer IRC meetings are available at http://dri.sourceforge.net/IRC-logs/ . <-- seems to be dead.
IRC logs (#dri-devel/#nouveau/#radeon/#radeonhd, started from 2009-10-01) at freedesktop: DRI logs