My son (2 years, 1 month) is just starting to show signs of wanting to go to the potty. He'll say "potty, potty, potty" but it's usually after he pooped. If we put him on the potty to pee, sometimes he'll go, sometimes he won't...but when he does, he cheers for himself (so he definitely is beginning to connect it with a positive experience).
His twin sister, on the other hand, could care less. She'll sit on the potty, but usually gets up after a minute, opens the cabinet where I keep their diapers and tries to put one on herself.
Anyone try underwear under diapers - so at least they can feel the wet? How did it go?