I have iTunes (10.6 40) and Match on my mac, as soon as I enabled match my "genius" playlists no longer work.
If I click genius on a track that is playing it says:
Genius is unavailable for the song "Don't Drop It"
I click "Update Genius" and it says that the results have been updated, but never makes it available.
I have over 10K songs, so surely it can find a genius result for a G-Love or Jack Johnson song... but it never does.