A Facebook Sixth Sense
So, as a code example, fine---but I'd caution against actually using this with your friends unless you know they're okay with it.  They will be acting under certain social expectations with regard to when and how people can see their typing notifications based on when and how they were able to see them before, and if you tweak your way into getting more access without your conversation partners knowing it beforehand, you're at least being sneaky, and possibly creepy or rude depending on the attitudes of your circle.  The flow of the machine transmissions doesn't currently constitute something visible enough to hang social norms off of, so be careful not to treat it as the anchor for them by mistake.  (This applies to other implementations of similar things, as well, such as "Psychic Mode" for Pidgin.)