There is an update to the Back Compat update that went out last week. This update does NOT add any new titles to the list, but rather fixes some audio issues. The back compat team game me this information to share:
“Today we’ve released a compatibility update to resolve the loss of audio problem some customers outside of North America and Asia were experiencing with the March update. The Backwards Compatibility product is complex and we committed an error when building the package to release on Live. These issues are now resolved.”
This update is now available via Xbox Live (when you play an original Xbox title you’ll get prompted for the update.)
Note: It may take a couple of hours before the updated version appears on the website (it has to be loaded on a lot of download servers) so if you have live…just grab it from there. Again, no new titles were added to the list.