America Olivo, who I've never heard of before, will have a supporting role in Iron Man. According to her website she will play a "Dubai beauty" in the film.
I guess she's done some TV work and has appeared in music videos in the past.
I don't know how large her role in the film will be... if she's from Dubai she'll be appearing early on in the movie and will probably (although this is speculation) not be in the majority of the film. Her IMDB.com page doesn't even list Iron Man there yet.
But hey, she's attractive and therefore newsworthy, right? ;-)