Nothing exists unless it’s written down, in one place. I prefer email, or a web-based forum system inside which all art feedback exists.
When I start on a project, I find out or choose the one single form of official, recorded communication, and hold people to using it. It’s fine in IM for quick back-and-forth, but that information gets summarized and send out via email, recorded in documentation\wiki\Basecamp where necessary, or put on a collaborative forum. If not, it’s not real. If it’s official and it’s going to happen, it’s going to happen and be recorded in only one place.
For face-to-face meetings, I’m always working as a go-between for design and art, and often programming as well. I take copious notes, work down my list of questions, then make peoples’ ideas fight if necessary. Once that’s done, I have a full written summary that everyone verbally signs off on before they leave the room, then that list gets emailed\integrated into the project plan and documentation with full details on what was discussed, next steps, and who was in the room. Paper trail, accountability, and it’s another way to make sure everyone’s on the same page since (if they read it) they’ll have processed that information both aurally and visually, and those run through different filters.
All information only exists in one place. And unless it’s in front of or accessible to everybody (as far as day-to-day development goes across disciplines), it’s not official. And sometimes I’ve had to be a dick about it, but the time it saves is simply unreal. :)