@ Greg B and Mark S - Nancy Wilson is/was the guitar player in Heart, her sister Ann the vocalist.

Back on topic, in the bluegrass field, I recently saw a very impressive young flatpicking guitar player, Courtney Hartman, who is part of the all-female band Della Mae. I saw them a few times in Germany and her guitar breaks were really fantastic. She's still a student at Berklee College of Music and apparently started out on fiddle!

Here's a clip:
Courtney plays Billy in the Lowground (with mando and fiddle)

Courtney Hartman website