If you go to the TSA website, and then do a search for knitting needles, it will be able to tell you...also you could do a search here, as this topic has been discussed.
But basically...they prefer wood to metal, straight to circs (I think, or is it the other way around???) Hmm...I took my circ bamboo's on with no problem.
BUT...a lot of it depends on the agent. Has anybody had anything confiscated??? or not really confiscated, but not allowed?