Quite a bit late in coming, but I wasn't chosen as a speaker for JavaOne 2008. Based on the presentations they've picked, I think I had the problem of being slightly off the topics they wanted to cover and trying to cover too much in one presentation. I may try again this November if I feel that I can craft a presentation they're more likely to accept.
Also, they never contacted me at all except to indicate I hadn't been chosen. Again, not surprising considering how many they had to review, but it suggests you should assume that you won't get a chance to clarify anything for the judges after you've submitted.