I've done many in 24p -- just so long as you deliver it on a format that the broadcaster can air (which usually means BetaSP, DV or DVD) then you'll be fine. Ask the stations what formats they accept, and you'll have to dub your footage over to that format. But 24p works very well for commercials.
i think Barry is refering to the format in terms of media used. My local staions want to be given a Beta tape. Just call a local station and ask if you deliver a fully produced commercial what format do they need and they should be gald to tell you