I spent my day at APS headquarters sorting abstracts for the March Meeting, the big condensed matter gathering that now approaches 7000 talks and posters. This is the second time I've done this, and it's always an interesting experience. When people submit abstracts they are supposed to choose a sorting category so that their talk ends up in an appropriate session - that way the audience will hopefully include people that actually are interested in the subject of the work. The contributed talks at the March Meeting are each 10 minutes, with 2 minutes for questions. Often these talks are the first chance a graduate student gets to present their work in a public forum before other scientists. Unfortunately 10 minutes is very short, so much so that often only near-experts in an area can get much out of such a brief explanation of results. There are also invited talks that are 30 minutes with 6 minutes for questions. These can be arranged in Invited Sessions, where all the talks are invited, and the session theme and potential speakers are nominated and voted upon by the program committee. Alternately, there are mixed Focus Topic sessions that typically have one or two invited talks mixed in with contributed ones.
The first big challenge in sorting the abstracts is that the sorting categories often overlap. For example, there were at least four different categories where people could have submitted abstracts about electronic properties of quantum dots. Surprisingly, about 80 people pushing around 7000 slips of barcoded paper is a reasonably efficient way of sorting. The second major issue in organizing the meeting is that space is very limited, and sessions are highly constrained - you don't want a contributed session to take place at the same time as an invited session on a closely related area, for example.
Helping to put together meetings like this is a bit like the scientific equivalent of jury duty. You want to make sure that it gets done well by people whose judgment you trust, but you don't want to have to do it yourself very often. It is a good way to get meet your fellow physicists, though.