No, not at all. I'm trying to think whose part she is taking since she doesn't have one of her own. On some of the websites they have pictures of her coming to Helm's Deep. Why? Does she join up with Aragorn and go with him on the Paths of the Death, etc? As long as she doesn't take Merry's place in the slaying of the Witch-King... I guess I won't mind if she becomes the "4th" member of the Aragorn group.
And, I think in the preview when Galadriel is talking, she might be talking to Gandalf. Doesn't the Eagle King take Gandalf to Lothlorien after he escapes from the Balrog? So, maybe Galdriel is filling Gandalf in, bringing him up to speed.
Yes, Gwahir takes Gandalf to Lothlorien (I won't say anything about snoots :) ) after the Balrog encounter.
So far, Arwen has Glorfindel's part and stolen Frodo's thunder at the fords. I expect she has Halbarad's part and probably her brothers' as well. If she take's Merry's part as Nazgul-slayer all the elf-bashing promises are off!!!