The biggest difference with 2009.06 is that there is (finally!) a SPARC version. It looks like I will be able to install OpenSolaris on my Sun Fire v100 after an OpenBoot Prom update
In the meantime, I have installed it in VirtualBox:
» Network Virtualization with Crossbow
» Turn any host into a SCSI target with COMSTAR
» Host virtual guests using xVM Hypervisor or LDoms
» SPARC® support for Distro Constructor, Auto Install, and Snap
» Intel Xeon 5500 processor support with deep power management
» MySQL and PHP DTrace Probes in the WebStack
» Improved usability of the package management system
» ZFS Time Slider Snapshot Management
» Contribute new applications with SourceJuicer
» Get 24/7 support with OpenSolaris Subscriptions
Again, you can order a free OpenSolaris install disk here.
Download the iso here. Make sure not to download the Auto Install version unless you know what it is.