For the first technical session I tried to see Doug Lea talk about concurrency utilities. He's the guy behind the famed util.concurrent library and a good speaker to boot. But when I got there, the doors were shut with a sign "Session Full". Even when someone left they wouldn't let anyone new in. So I wandered by the JavaServer Faces talk. Wouldn't ya know, it has a "Session Full" sign too.
Maybe this is a good sign that people are still coming to JavaOne. Maybe it's a bad sign that they didn't book bigger rooms. But the practical moral of the story is: show up early or don't show up at all.