TotalNet Advanced Server (TAS) has been IBM's preferred ClearCase interop solution for many years. Yet, we recieved a piece of notification from LSI saying that TAS would be end of support in 60 days. And that was more than one month ago.
Many commercial and free software implement file systems sharing from UNIX to Windows. All use one of the two protocols: NFS and SMB. For ClearCase interop, we can either set up a SMB server on the UNIX side, or install NFS clients on every Windows box. For NFS, there are many commercial software, such as Netapp, EMC, Humming Bird Maestro, etc. For SBM, there is TAS. Of course we have Samba, but it is free. Who wants a free software?
We use Solaris VOB server in our ClearCase environment. From Solaris 10, Samba is bundled with the OS. Maybe we will use Solaris's native CIFS (Common Internet File System) solution some day.