I only took one picture at Webmasterworld Boston Pubcon last week, but SeoBook took many at the Pubcon Wrapup Party and they’re worth a look.
The 2006 Boston Pubcon was great. It was rather small (with about 900 in attendance) but being rather small made it easy to connect with other people. You could go talk to Matt Cutts for like 10 to 20 minutes without having swarms and swarms of people surrounding you.
That’s larger than I thought - to me it looked more like 500-600 people.