David Israel (aka Smite Matter) looks like the prominent member of the avant garde on this one. Check out his blog at http://smitematter.com/
"Pioneering the creation of inspired, professional ambient electronic music on the Apple iPad. Proudly one of the first recording artists to use any iDevice exclusively for all serious music composition and production. Offering insight, advice, app reviews, opinion, and sharing of knowledge."
His stuff's on Soundcloud, and it's durn good! http://soundcloud.com/smite-matter