I don't think I'm revealing any big secret by saying I'm currently at the SIGCOMM PC meeting. So far, it's what you'd expect -- a crowded room of 30+ people, hashing out what papers we actually want to accept. Lots of discussion, some of it contentious, but no big fights (yet).
I'm realizing that a possible downside of bigger PCs (which I think theory conferences could use) is that just logistically it's harder to have over 30 people in a room having these sorts of discussions. It's harder to hear and see everyone. When it's your turn to talk, talk loud.
An interesting logistic difference is that we're discussing papers in numerical order by topic, not ranked by score. I'm still absorbing how well this works. (I've found it nice in other PCs to start at the top and bottom and quickly accept and reject "easy papers". This is different.)
People are removed from the room for conflicts. There are papers where I can't see the reviews or anything beyond the paper title. Yet we soldier on. Seriously, this is not a big deal. Being outside is a good chance to talk to people. There are plenty of non-conflicted people to offer opinions, of course, so the issue brought up by theory people that conflicted people need to be around so you have enough knowledgeable people doesn't arise. (Of course, I think it comes up much less in theory than people argue.)
After having chaired STOC, it's very nice to sit back and participate in a PC meeting without being a chair. I even have time to blog about it.