I don't know if she's been nominated or not, but she's done a lot of covers for books I like, to the point where I'll always check out something she's done the cover for: Kinuko Craft.

Otherwise I tend not to pay attention to who does cover art. The last two years since I've been voting for Hugos I do a bit more but I also have a kindle so don't look at book covers much in real life. The pictures that come with the Hugo packet though, wow. That's probably the hardest choice for me.