I looks like both OpenSolaris and the next update of Solaris 10 will be getting a updated version of Samba.
This is probably most interesting for Solaris 10 since OpenSolaris has it's own native implementation of CIFS in the kernel. This update is needed for comparability with Windows 7 which requires version 3.4 of Samba.
Some details from the PSARC:
"Samba is the only available CIFS volume and printing server in Solaris 10 and 9 (production releases of the Solaris).
Samba is the only available CIFS printing server in Solaris 9 and above.
Besides Apache, Samba is the most important component in Solaris in the case of the business deployment. It plays primary role in interoperability with the MS Windows on Solaris 10 and 9.
Samba.org community discontinued support of the Samba 3.0.x currently bundled with all releases of Solaris."
Update Samba to release 3.4 [PSARC/2009/682]
CR 6852659, Update samba to 3.3.5 or later
Talks I have given
5 months ago