so far i have put unused colour neg and slide film on hand luggage (and then exposed film on the return trip) and it does not seem to be a problem. i have read that checked-in luggage goes through larger machines which can potentially zap film - never tried.
to be very safe i guess you can ask them to hand-inspect.
i looked up some other photog's experiences, and this one looks interesting enough:
http://www.scottpix.com/faqs/f162.html