My oldest was almost 2 1/2 when he started sleeping through and my second still doesn't sleep more than 2 hours at a time and he is almost 1 1/2. I've read that it's a developmental thing and they will sleep through the night when they are ready.
@cubanese, oh wow. I don't mind it too much, I'm just so sleepy. Lol
Mine did from the day she was born