Needles are totally ok on planes. I flew over the holiday and took bamboo straights and circs on my carry-on without a second glance. I did put my metals in my checked bag just to be safe. I also bought one of the Clover cutting medallion thingys and carried that back with no problems. They are a great substitute for scissors.
However, I did print the page from TSA's website that says they are allowed - just in case!
Oh - if you do knit on the plane I would recommend sitting by the window so you don't get thirty million questions while you are trying to count your short rows for the clogs!! :rollseyes: