This is a neat idea (if not technically all that novel)… log in to Sun Learning Services portal, and you can play with a virtual instance of OpenSolaris for up to an hour.
It does require Java, there are only 8 slots available at any one time, and right now they’re still provisioning OpenSolaris 2008.11 rather than the newer and shinier 2009.06. But if you want to give OpenSolaris a quick whirl, you might find it more convenient than downloading the LiveCD.
More info in Brian Leonard’s blog entry.