Recently did a trip with a friend, 4 flights with a tripod in his hand luggage. No problem on the first 3 flights, on the final flight home from Lisbon it was confiscated for being a 'blunt object'. So it's evident that most airports don't seem to care and you'd probably get away with it, however if you can't afford to have it taken away from you then best not take it.
P.S. It was only a mini tripod, it was mainly plastic with a few metal components and it was about 20cm tall when folded up.