i totally agree with kristie on the routine thing. it used to take 1-2 hours of laying in bed nursing for carter to fall asleep. but once we got a real routine...dinner, quiet play, bath, massage, book and nurse, to the crib....it all changed. now i can put him in the crib awake and he'll fall asleep on his own in a few minutes. as long as we completed his routine. and i've noticed that as we go on, he sleeps longer through the night. we're up to almost no wakings (hope i didn't just jinx myself!!). he wakes up at 6 no matter what time he goes to sleep but i can handle it if he is sleeping through the night. hth.
Another thing that helps us is to keep a consistant bedtime routine. In our house it's bath, massage, books, nurse, sleep. Even if we have to put him down a little early or late, he always knows sleep follows that pattern and that seems to really help.