Version 1.0 of Sun's Logical Domains product is now released!
If you own (or have access to) a UltraSPARC-T1 (aka "Niagara") processor based machine this is for you. If you don't have one go here.
You can find all the relevant bits on the download page, and it is free.
Up to 32 separate virtual machines - each with its own OS instance running on a single cool threads chip.
For a demo click here!
The product is delivered as a firmware upgrade for your platform that includes the domaining capable Hypervisor as well as updates to the service processor. In addition there are updates for Solaris 10, including the domain manager package that configures and manages your platform's virtual machines.