Comment 17 for bug 1009816

Interesting. I could fix this in Ubuntu itself now by using CompizConfig to set focus_prevention_level from low to high. Maybe some update had actually changed this setting because now everything behaves as it used to, i.e. the Firefox window wiggles in the task bar but doesn't go to the foreground.
I did actually update Ubuntu two versions or so to 12.04 recently but I'm sure this change had happened before that.