The core team recently began holding daily office hours in IRC (in the form of bug scrubs). I would like to extend them to the UI team as well, to encourage frequent discussion of core UI issues for 3.5. Office hours will allow newer contributors to become more involved and hopefully help keep the weekly UI chats a bit shorter in length.
Weekdays @ 19:00 UTC in #wordpress-ui
For development office hours, go to #wordpress-dev — same time, different place.