Who was the woman that jonathon ross and dara o brien was taking the mickey out !

Who was the woman that jonathon ross and dara o brien was taking the mickey out of at live earth?

she had brown hair and a guitar and got little or no reaction. the end of the song, it cut to Ross and OBrien who said something like "well, al picked her, not our fault"

3 weeks ago
not katie melua/kt tunstall. she looked american

I know who you mean, just dont mind her name.