I'm posting this here, because I can only reproduce this on _64 machines.
Following a PM, I was lead to investigate 'chat' in FB. Which I know was working. But as I hardly ever use FB I didn't notice.
So far I established on 12.1 _64 installs Gnome and KDE it's not working. Also on Mint 13 _64,not working.
On 12.1 and 12.2 x86 it is working
Browsers tested: Firefox, Opera, Seamonkey, Konq