From an Open Group mailing list post:

We are delighted to announce that Sun Microsystems has registered Solaris 10 on their SPARC and X86 platforms as conforming to the UNIX 03 Product Standard.

* Solaris 10 Operating System – on 32-bit & 64-bit SPARC based systems
* Solaris 10 Operating System – on 32-bit X86 based systems
* Solaris 10 Operating System – on 64-bit X86 based systems

The Conformance Statements will be available in the next few days at http://www.opengroup.org/csq/
For more information on UNIX 03, please refer to http://www.unix.org/unix03.html
For the latest official list of UNIX registered products, please refer to http://www.opengroup.org/openbrand/register/