All of those things are fairly trivial for FB to track. Age (obvious), Location (trackable through Places, geolocation, etc. through that thing in your pocket),

All of those things are fairly trivial for FB to track. Age (obvious), Location (trackable through Places, geolocation, etc. through that thing in your pocket), Gender (presumably you would post a status update about something that big?), Employment (status, amassing colleagues as 'friends'?). It seems like they've hit on a constantly self-updating demographic info machine...