Solaris 11 is available for download "SunOS Release 5.11 Version 11.0", based on build snv_175b.
There are of course many changes since Solaris 10, most of them have been available in the latest build of OpenSolaris but there are some new that are unique to the final release of Solaris 11.
Install images are available for download and works on all current SPARC machines which is the T and M-series. There are also images available for X86-based machines which also can be used in VirtualBox. Here is a quick reference for the brand new packaging system: IPS one liners.
I will post more detailed follow-up after I've had time to test it for more than a few hours.
Oracle Solaris 11 11/11 – What’s new
Download Oracle Solaris 11
Future features of Solaris 11