The first session I attended was OpenSSO, delivered by Sang Shin
OpenSSO looks very promising. A very modular design of the framework allows to use virtually any authentication scheme.
Next, I attended a session about DTrace, quite a powerful tool for monitoring your applications.
Also, JSR-290 looks very promising!
I also attended the superb talk by Yakov Sirotkin, about organizing the asynchronous jobs using the Oracle AQ.
Also, VirtualBox have been advertised quite heavily.