Now they've moved on to discussing one of the most-requested features from developers is a way to track whether or not someone is using an application. Apple notes that one of the solutions is to allow for backgroud processes. While that would seem appealing (Windows Mobile has been doing this), it is actually terrible for your battery life. Don't worry though, Apple does have a solution.
Apple has created a push notification service which will be distributed to all developers. Essentially the iPhone will keep a steady connection to the Apple servers. When you quit an application, updates are shuffled from the server to your iPhone.
We won't be seeing this functionality until September, however, developers should be getting their hands on this very soon.