I'm not sure how it is working for other songs but the grey mist raider bard song ( level 8 ) seems to be working rather sporadically. I'm seeing about a 25% chance that the bard song either does not work, casts on your party but not you, or only a few people around you. Earlier I used it three times with no effect, then another bard within our party with the same song ( not level 8 ) casted and it worked.
http://www.efupw.com/forums/showthread.php?t=100039