While it may have been in beta longer, facebook rolled out facial recognition and memories just this month alone.
Memories is a new option on the left-hand side of your profile (that I haven't found a way to mark private yet). It allows you to view certain actions for each year you've been a facebook member. At launch, it shows per year: tagged photos, new friends, new likes, how many times you've clicked like and also random status updates from you (they rotate on refresh - not sure how they're pulling). This was so huge on 12/16/2010 that many people were tweeting that facebook was down for the count (it was REALLY slow)! Facebook may have accidently made this feature live, as it's been removed...for now.
Facial recognition is now being used for photo tagging suggestions. Whenever you upload a new photo to your facebook account, it will use facial recognition software to suggest who you tag. It basically makes the facebook photo tagging process easier to ensure more use of the feature. It's also pretty cool if you do a screen capture to make a collage of yourself ;)