Phoronix has a review and pics of the first development release of OpenSolaris Project Indiana.
After downloading this ISO (the Developer Preview is only 629MB), the image can be burned to a disc and immediately booted. Project Indiana incorporates a “Slim Install” LiveCD for x86 systems. Just like Ubuntu, Fedora Live, and a number of other Linux distributions, you can boot to this CD and start using it without ever touching the contents of your hard drive.