for the album auto-tagger, MB is currently only using musicbrainz
MB uses freedb for CD tracks only
i do plan to add discogs and now you mention it, also no reason not to include freedb as a fallback when no match found
Excellent idea

There are many enhancements suggested for the Auto-Tagger on the Wishlist, but these two improvements would definitely move this tool to the next level.
AntiPOP your comparison of Foobar and MB autotagging capabilities seems to be great stimulus for the long awaited changes

I guess when the enhancements are implemented, no one would even think about using any other app for auto-tagging

+1
I used many other apps for tagging my audio collection and MB Auto-Tager and Tag Editor is definitely the best one in terms of usability (excellent GUI !!!). But there is certainly room for the improvements when it comes to effectiveness, so adding more web services is a major step forward.