Zimbra Desktop for Solaris is finally available for download. This is for x86 systems only though. It runs on both OpenSolaris as well as Solaris 10U5. Not sure about older versions of Solaris 10 though.
This build is based on the 5.0.10 version of the Zimbra source code. This will go nicely with the ZCS binary that Dom Ijichi has built and is available in the same location (SourceForge.net: Zimbra Community Builds).
Unlike the other platforms (Linux/Win/Mac), this does not have an installer. Extract the tarball and run. The notes section have some instructions on how to run.
Please let know if there are any issues.