Again from the Get It page, comment three:
For users who want to install OpenSolaris in as few steps as possible, the instructions are a bit confusing. If you jump past the “Download the Live CD” and “Try out the LiveCD” headlines, here's what you see:
Install OpenSolaris Developer Preview
Should you like your experience with the OpenSolaris Developer Preview, you may like to install it to your system. You can execute the OpenSolaris installer by clicking on the Install OpenSolaris icon on your desktop. For detailed installation instructions, see OpenSolaris Installation Documentation.
I'd assumed that installation files and Live CD files would be available in separate downloads. It wasn't, so I read the installation section a few times before figuring out that I had to back up and create a Live CD. Perhaps the paragraph could instead read:
Install OpenSolaris Developer Preview
Start by downloading the OpenSolaris Developer Preview Live CD, which contains all necessary installation files. Boot your computer from the Live CD and tinker around a bit. Like what you see? Begin installing OpenSolaris by double-clicking on the Install OpenSolaris icon on your desktop. For more detailed instructions, see OpenSolaris
Installation Documentation.