I have noticed that audioscrobbler plugin submits wrong data to last.fm. When I play AC/DC it will be coverted to AC+DC. I am not only one, last week there was at least 38 users who had played AC+DC and many of them belong to last.fms mediaportal group.
http://www.last.fm/music/AC%2BDC
EDIT: I use MP stable 0.2.2.0 but tried latest svn 2007-03-25 and both subit wrong data to last.fm
http://www.last.fm/music/AC%2BDC
EDIT: I use MP stable 0.2.2.0 but tried latest svn 2007-03-25 and both subit wrong data to last.fm