There have been a lot buzz surrounding Sun’s Project Indiana. The first information about the project surfaced many months ago, but Sun has been unwilling to disclose much at all about Project Indiana. Well today the open source and binary distribution was released to the public, although in the shape of a developers preview, and much like most major Linux distributions you can download it as a LiveCD to try out first and install later. Project Indiana uses the Gnome Desktop Environment by default and a skin similar to Clearlooks, which is quite different from the regular Solaris look.
You can create and customize your own distribution through the Distribution Constructor ToolKit, while Snap Upgrade and IPS (Image Package System) will make it easy to keep your system up to date, and to add and remove applications and various software.
More information can be found at the OpenSolaris website, where you can also download the Developers Preview.