T.B.
Do you know why he is waking up? Is he potty trained and has to go potty? Is it a bad dream? Does he speak well enough to tell you what is going on at all? I know most 2 year olds cannot, but if he is a good talker, it might help to figure out what has him waking up. If you are potty training him, ask him if he has to go on the potty- maybe that is the issue and he's trying to go there instead of in a diaper/ pull-up?
My son's story was JUST like yours- horrible sleeper and colic in the beginning. He would wake 4-6 times/ night- it was horrible and I was a wreck from lack of sleep. When he was about 8 months old, I started reading a lot of sleep books looking for ideas on how to get him to sleep better. We tried everything short of Crying It Out, but nothing worked. In the end, we did CIO, as a last resort. It worked, but now that he is potty trained (at night too), it has started up again, and I hate to just let him cry because he might have to go potty. So, we talked with him (my son is very verbal) and explained that he needed to stop crying at night, and that if he did, he'd get a surprise in the morning. Believe it or not, it's been working. If he's not feeling well (we all had the flu last week), he will wake up a few times, but if he's feeling ok, he's been sleeping (or at least putting himself back to sleep) through the night. Maybe you can try some kind of reward for good sleeping- but make sure it's worth it. My son will do just about anything for a Matchbox car, so we use that for lots of big things that he does. You might want to talk to him and tell him that you and Daddy are very tired and need to sleep, and that if he gets up in the night, you cannot come to him because you need to sleep. 2 year olds have the ability to understand a lot. I would try telling him what you are going to do, then do it and see what happens. At least you have talked to him about it, so it will not be a surprise. Tell him you need him to go back to sleep, and he needs to wait until Mr. Sun is up before you will come and get him.
I hope that is helpful in some way...
Good luck,
T.