UBB.threads has never had a built in Sitemaps script, so I took the time in 2007 to begin writing a very involved (multiple types of sitemaps, long runs of testing, continuously updated since its release).
Some links:
Information & Purchase: VNC Web Services
UBB.SitemapsDocumentation: UBBWiki
UBB.SitemapsPublic Support: UBBDev
7.x UBB.SitemapsListing of my relevant 3rd party scripts: VNC Web Services
Script Listing