T.C.
I agree with Stephanie. Determine what his 'currency' is and deny him of it. Start with two days. 2 days of no TV, or bike riding or game boy or whatever. And add a day with each ensuing infraction.
I just read an article recently that said that by the time the kids are 12 and 13 if you see this type of behaviour - the parenting is over. For the most part, I agree with that. And the point here is that you have to get this under control now. So keep on trying. Be persistent and the hardest of all - follow through. do not threaten. DO!
State the consequences clearly. give a warning. One warning. and then if he does not comply - go right to the consequences.
Good luck - and hang tough!