I'm much in the same boat as TheDirt. I can hum and replicate melodies and notes on the guitar without too much trouble. Sometimes I can tell which notes are played without having to pick up the guitar and figure them out. I don't think it has anything to do with perfect pitch though. I've just heard and played the same notes and chords so many times, it becomes second nature.

As for learning perfect pitch . . . I'll have to go along with everyone else in saying that that's impossible. I've seen a lot of the same ads, so just remember, if it sounds (no pun intended) too good to be true, it probably is.