POSSCON, now in its third fourth year has both grown and matured. The Columbia, SC conference pulls in a number of great speakers, this year including Joe "Zonker" Brockmeier, Walter Bender, Leslie Hawthorne, and Jon "Maddog" Hall.
The attendance appeared (at least to my calibrated counting eyes) to have around 300 attendees each day. One of POSSCON's more unusual features compared to the majority of F/LOSS conferences is that it was held during the week (Wednesday through Friday). The other distinguishing factor is that the audience is largely composed of college students and business types. This fact was brought home during Joe Brockmeier's keynote when he asked the audience how many people knew who Richard Stallman is, and 90% of the audience indicated that they did not. Nor did they show much recognition of other concepts that would be familiar to the common open source conference-goer.
But another attendee pointed out to me that this was actually a good thing--it's evidence of the mainstreaming of F/LOSS. Three hundred people who largely don't know anything about open source paid $90 and spent three days of their time to come learn about open source. That speaks volumes to the organizers of POSSCON accomplishing their goals.
I also noted that POSSCON appears to be maturing culturally. In true open source fashion, the conference giveaways shifted from iPads last year to Android tablets this year. The conference staff were also using Android tablets for surveys and registration check-in.
Finally, POSSCON takes great care of its attendees, with sumptuous snacks, drinks, and meals provided at every opportunity. In short, if you are in the southeast and aren't already attending POSSCON, you should add it to your list of conferences to attend.