The annual JVM Summit is due to start in a couple of days (July 26-28, 2010) at Oracle's Sun Santa Clara campus. It's a chance for VM implementers to get together and talk about (amongst other things) the latest JVM optimizations for Java and other programming languages. A full schedule can be found on the JVM Summit wiki. The presentations will be recorded and uploaded at some point in the future. In the meantime, if you want to see what was presented in 2009 the videos are still on the InfoQ site.
To find out more about the JVM and the upcoming JVM Summit have a look at the latest TechCast Live recording - Toward a Universal VM (it's about 30 minutes long).