Sigh, Firefox 6 doesn't support it Rated 5 out of 5 stars
I'm running Ubuntu 11.10 on a testbed partition, and Firefox 6 is the installed version. FloatNotes isn't currently compatible and I look forward to seeing the two working together again.
I runs beautifully on FF5
Edit: Oh I thought there is a real problem with addon. But it seems work fine with FF6 and I updated the version info.