(Edit: As I looked at the title I realized it appears I am complaining about the characters race or sex. I am not. I am perfectly fine with both. Some of my favorite characters are Luke Cage, Rogue, and Jean Grey, and Gravedigger from DC's WWII comics. Point being I screwed up on the title and I apologize, I was just trying to make it clear who we were talking about since I don't think everyone knows the character is changing.)
Obviously she wasn't going to be known as Iron Man (unless she is a FTM transsexual and no one has mentioned it, but I find that unlikely), but come on Ironheart. That is like the laziest possible name. Not only does it not sound good coming off the tongue it sounds like a cheap Jean-Claude Van Damme movie.
Personally I would have gone with something like FerroGyn which sounds cool (but is probably insulting) or something with Steel in it. I thought about Steel Resolve but that sounds like a bad beer. Lady Steel doesn't sound bad but I am pretty sure that there is a already a character with a variation of that name (actually there isn't according to my 30 sec google search)
I guess we have to go with Iron Maiden. Then she can get a really ugly sidekick named Eddie and our theme will be complete.
Another option, since she is caged in the suit would be Caged Fury.
or my personal favorite Fred. Simple easy to remember and it rolls off the tongue. Definitely it should be Fred.
(In case you have guessed I am generally not a fan of the new Iron Man, at least from what I have seen so far. I don't mind the female part or the African-American part but the origin, as I have heard it so far deviates to far from the tenets of the character for me. )