Surakarta for the iPhone/iPod Touch is now available for download. (Link opens in iTunes.) I haven’t yet been able to find it directly by searching, but hopefully the App Store index will update shortly.
I’m currently working on version 1.1, where I’ll add single-player support. In the meantime, download Surakarta and write a review!
UPDATE (6:04 pm): Sometime in the last 10 minutes, it showed up through search. Hooray!