I'd flip through No-Cry Sleep Solution and especially the Sears Nighttime Parenting Book. No-Cry tends to be for younger children, but I'm sure that some of the ideas will help, and it's good to have solid knowledge of some of the base rules for good sleep just to make sure you've got all of your bases covered. Nighttime Parenting also has some excellent advice for how to get a child back into his own bed from your own. The basic idea is to do it gradually - say, over hte course of a few weeks, but really just let things work for your family based on how things progress. You first have him sleep at the foot of your bed in a sleeping bag or a little mattress or whatever. After a few nights or a week or so, move it closer to the door. Give him stars or a chart or rewards for X number of nights that he stays put. Make it all very positive, and try to keep looking to the ultimate goal. Make it okay for him to return to your bed on tough nights, but keep encouraging him. The less stress he feels around this, the more effective it all is, because of course stress affects sleep.
After not very long, he can sleep just outside your door - maybe, at first, with the door open a bit; then, open less; then, just open a crack, over the course of several nights or a week (or two if he's having a hard time with it). Maybe help him build a little sleep nook/fort somewhere in the house, and that can be his special place for a while. Help him decorate it according to his favorite, non-scary, theme. At bedtime, take a flashlight and read him a story before bed. He might really like that! Maybe he won't be in *his* bed in *his* room for a while, but at least he will enjoy it enough to be out of yours! And of course, once he feels ready, he can either gradually move to his bedroom, or take that big step one day, and you can have a little ceremony or party - maybe this will be in December, and coincide with his birthday, as he's becoming such a big boy.
Of course, depending on how things go, and what other great advice in these books works for you, it might be much sooner than that, that you see your son sleeping soundly in his own bed, in his room!
Techniques aside, if he's dealing with a sleep *disorder*, then neurofeedback might be your greatest help. It can also enhance the process I just described by helping to calm your son and get him used to having sleepy feelings away from snuggling with Mom and Dad. It acts as white noise, but instead of just being some new, loud, unfamiliar noise - which would be very hard for anyone to adjust to when they're used to sleeping in silence or a very quiet room - the sleep sessions actually induce sleep. It's very safe, there are no side effects, and it can have good other effects, such as a strengthened immune system (i don't know how that works, but it does).
I like http://www.brainsync.com/product.asp?specific=142 and http://www.brainsync.com/product.asp?specific=156 They need to be played *in stereo*. This is very important. You son can listen to it with headphones, or you can place two stereos near the head of his bed, one on either side. You also need to play it at a volume that allows him to hear it well, i.e., not barely audible with the intention of letting him "sleep through the noise." He needs to be able to hear it well in order for it to work, and even if it's pretty loud, he'll sleep, anyway.
You'll do great. Get Nighttime Parenting by Dr. Sears! You will be so relieved!
L.