Hi S. -
It depends on how you want to handle the situation. I read once that we parents should "start as we intend to go". In other words, if you are not an advocate of co-sleeping, then I would not bring him back to bed with you. There is absolutely nothing wrong with doing so (IMO), but if you don't intend to keep it that way, it may be short term relief, but long term issues for your family as it will complicate getting your son to sleep in his crib.
There are a lot of approaches, you just have to find the one that is right for you and your son. I have never been able to let my son cry-it-out, so I used the "put down method". I would go in and lay him back down and talk softly touching him... just until he was calm. Then I would leave. If he cried again, I would repeat. THis is extremely hard on you and can be time consuming, so you really have to commit and just stick with it. But during the process, it is tough. I would respond to all night wakings this way. THis worked for me b/c I felt I was getting my point across that it was bedtime and that is where he would stay, but I wasn't leaving him in there to cry by himself.
THis is certainly only one of the many ways to address the situation and the only one I can really speak to b/c I have used it.
It is really difficult when kids wake or won't slepp and we are sleep deprived...I am living it right now as well! I think all we can do is be consistent and patient. So, decide how you want to handle the situation and stick with it as best you can. It may be exhausting for a little while, but in the end I am sure it will pay off!
Good luck.