I think it's a variation on a Karen Combs or Stone quilt.
Hang on....
(I always get those 2 confused)
It's a Karen Stone quilt.
http://ideagal.blogspot.com/2009/10/...009-vol-2.html
She won 1st place in Innovative piecing at Houston
Scroll down, it's in the middle of the page.
It's basically a clamshell quilt, but she went to down on putting amazing applique or piecing instead of using plain fabric.