The concurrency problem was partially and briefly covered in the Platforms state of the Union keynote. Since closures in Swift are compatible with Apple's C blocks extension, all of the libdispatch API works with it out of the box. and the last-argument-is-a-closure syntax from Ruby makes it really nice:

    dispatch_apply(arr.length, queue) {index in
        arr[index] = expensive_func(arr[index])
    }

Obviously nice wrappers can be written around code like this to give you safe parallel programming. You could also quite easily make futures/async stuff.