I think having scrobbling natively implemented would be a huge advantage. Especially, since scrobbles would be independent from renames (track/artist) then. It would also support NGS-style collaborations. Also, it could answer new questions (that last.fm will never be able to answer):

• What is my favorite song (as opposed to recording!)?
• What is my favorite composer (as opposed to credited artist!)

For the webservice, it should be made compatible with the AudioScrobbler API (for compatibility reasons), but only care for the submitted MBID.

Also, a script could be written to import from Last.fm, by e.g. matching the scrobbled tracks to local files (with MBID).

I would work on this next year, if this has any chance of getting merged. So, I would be glad for feedback!