Face Recognition software for the mac

I know that picaso now has this.
Is there any mac software that will allow you to teach you computer to recognise people by their faces and then tag it.

Its ok I have figured it out.
Use picasa albums, upload album from iphoto to picaso albums and you now have the ability to tag photos based on face recognition.
It is awesome !!
It tagged a picture of my son with his name but also my wifes...on closer inspection she was in a picture on the wall!!

Wow, I just gave this a try and it's pretty impressive - even just through the web interface...
I really like what Google is doing with Picasa.. hopefully Apple will step up a bit when Google releases a Mac version.