I checked this with the airport police in Dusseldorf a couple of years ago and was told a very definite no. A few months ago the guy in one of my local wool shops told me that plastic or wooden needles are allowed now but not metal. Others have told me that they bring the modular circular needles - they put the wooden needle part into a pencil case with other pens and pencils and just shove the connecting plastic part in somewhere else. If you're a member of ravelry you'll probably find lots of discussion on the topic there.
Personally, I've tended to stick with what I was told by the police. On the other hand I don't really fly anywhere that takes longer than an hour or two and can fill that time with a book. At the very least I'd take some cheap needles that I wouldn't be bothered about having to give up, just in case.
DAA doesn't include them on [broken link removed] but does have the somewhat catch-all "1.3. OBJECTS WITH A SHARP POINT OR SHARP EDGE – OBJECTS WITH A SHARP POINT OR SHARP EDGE CAPABLE OF BEING USED TO CAUSE SERIOUS INJURY..."