The demo from the WWDC keynote is quite impressive. Unfortunately, this site seems to have been slashdotted. (Basically, Swift is "Apple acquires their own LightTable.") It's touted as a language for parallelism. I'm curious about its concurrency primitives. Since distribution is shown as a top feature, I'm going to guess that it has an Erlang-like actor model.
Having ARC and not needing GC will end up being a big fundamental advantage for its parallelism story.