This is one of those things that makes Rubymotion am increasingly attractive prospect for me as an iOS developer. I wouldn't be ready to move off my familiar Objective-C stack quite yet, but if more projects like this one come along i might just consider it.

One thing I'm curious about is the support for TDD when using Rubymotion, there's a lot of Rspec clones out there for Objective-C but they all feel a bit hacky due to the language's less than stellar support for DSLs. On top of that, testing doesn't seem to be all that big a deal in the iOS world. I'm wondering if a healthy dose of the Ruby ethos changes this.