Building Basecamp for iPhone in RubyMotion
I’m really bullish about RubyMotion’s future, especially at 37signals. I think there’s a huge opportunity to make veteran iOS developers more productive by throwing the doors open to the Ruby community. New iOS developers win as well, since RubyMotion makes the jump to mobile development less scary by keeping your toolchain similar to other open source platforms.
Update (2013-02-16): Jason Zimdars writes about design decisions that they made.