I read somewhere that it's almost impossible to develop perfect pitch after you pass 10 (6? 8?) years of age
It's not the ears that worry me . it's my bleepin' eyes!

(how else am i gonna find those hearing aids)
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Pay careful attention to what uncle Bill "the Wise man" Says in his signature :
No-one remembers what you do or say. => (a Note is nothing in itself)
Everyone remembers how you made them feel. => (it's the relationship they are in with other notes that counts)

instead of remebering each note as an entity remember them in relations/intervals/groups of triads etc.
Like caged system , once you are able to play basic chords in all forms in all positons/inversions/harmonizing etc, you will start remembering the notes much easyly and start seeing the fretboard as a set of patterns of roots, 4th, 5ths etc.
Whatever method you choose, Do practice that a lot and incorporate that into your everyday playing, or you may end up making the same mistake i did i.e after memorizing i did not used it at all, moved on and forgot all of that.
And if you are keen on memorizing and learning fretboard then may i recommend this dvd to you.
http://www.licklibrary.com/store/jamie-humphries/15584/ultimate-guitar-fretboard-navigatorI had borrowed it once from a friend and it was very useful.
I like their concepts stuff quite a bit especially becasue there is no tablature so you really gotta pay attention and work your way through, or write down on paper if need be and that all basically helps you memorize.
~Amit
I Am A Man of Few Words Ironically Understandable by the Select Few, hence more often than not I have to Come out of my Manhood to do the obvious. Now Ain't it a cruel world?