Comment 2 for bug 584513

Same problem here. Another easy way to reproduce, is to add a Firefox launcher to the panel, then click on an empty space on the desktop and start Firefox with the launcher.
Same happens when I click on a link in any program (Liferea, Gnome-terminal, ...), Firefox will open, but beneath all other windows and won't have focus neither.

Sometimes (very little) it does work. Mostly when starting from the menu (Applications=>Internet=>Firefox), but it is very unpredictable.