Basecamp for iPhone made with RubyMotion

Nick Quaranto at 37 Signals describes writing the Basecamp app with RubyMotion so he could avoid using Xcode and learning Objective-C.

When I started developing iOS apps, I looked at using MonoTouch as I had been writing C# for many years. But I decided the pitfalls of using a third-party layer on top of Objective-C and Cocoa just wasn't worth it. Objective-C isn't a very hard language to learn, and I can't help but think that these kind of tools just encourage developer laziness.