I had no problem carrying mine on, nobody said anything about it. I did find that when we flew down, on NWA, they didn't offer to hang my dress but flying back on Delta, on both flights they offered to take it and hang it in their closet for me. Just watch if you lie it in the overhead compartments...some people show no concern and throw stuff on top of it - I ended up lying mine across peoples' luggage.
I just flew back with my wedding dress after the terrorist activity and did not have a problem. we were on US airways and some of the employees were really great about the wedding dress and hung it for me and others were not. I stated as soon as I got on the plane this is my wedding dress is there someplace safe I can place it. Inevtiably they found me a spot but were not always the nicest.