Again contrary to what has been said in the past, Oracle now supports Solaris on non-Oracle x86 systems as long as it’s listed as certified in the Solaris Hardware Compatibility List (HCL).
You can find more information on http://www.oracle.com/us/products/servers-storage/solaris/non-sun-x86-081976.html, including links to all the relevant pages.
No real mention of OpenSolaris, but then again it’s in development and you really shouldn’t run it in production unless you’re capable of supporting it yourself.