Matt Galloway with a great rundown of some highlights of Swift. You should, of course, read the language guide but if you haven't had time to run through that 500+ page tome then this is a nice introduction to some of the more interesting parts of it. You really should read the full book though, there is a huge amount to learn about this new language.
There are always going to be issues with a brand new language (especially one which has been kept secret) so this isn't criticism so much as a slight warning that if you jump in with both feet on Swift development in real apps then you are going to find issues. Markus Persson has a write up here of a small issue with bringing AFNetworking into Swift, even if you don't use AFNetworking this is an interesting dive into fixing this kind of problem. Also, check out the follow up post for a better solution to the original problem.
It's going to be so much fun learning this language over the next few months and Ash Furrow kicks us off at the beginning with a great guide to initialisers (yes, s not z 😄).
Since iOS 7 introduced silent, automatic updates to apps we have lost much of our ability to communicate with our users through release notes. Matt Zanchelli has taken a crack at the problem and produced this configurable "What's New" screen. My only caution with this is not to use it for every release but save it for when you really need to talk to people, give it some impact.