If you want to start playing around with Swift, I just put together a super simple app. It is a TO-DO app built on both apple languages.
It includes simple things like implementing tables, a navigation controller and a customisable button.
For those who already have some experience in Objective-C you'll feel the difference and even a bit of frustration, because the api changes remarkably, but don't be scare it is an amazing language.
Also for people who still have not tried Objective, I think the transition will be much easier. It is very similar to languages like Ruby, Python, etc ... which I think lowers the learning curve. I would say that this inspired a little RubyMotion.
So check out the app and let me know what do you think...