Great article at Ars again, this time examining the pros and cons of Apple’s push notifications in the iPhone.
There’s a lot of talk about background applications on the iPhone, and (as the article points out) for good reason especially for music streaming apps. But I’d tend to agree that most apps do not need to run in the background. IM apps only need to let me know when I get a new message.
With that in mind, I’d place the focus on the way notifications are handled on the iPhone OS right now. The modal notification window definitely seems to be lacking, and an icon badge might be too inconspicuous to get noticed (especially with the number of apps people have on their phones). Android or Palm’s WebOS handle notifications in a much better unobtrusive way. Fix that Apple, and things should already look much better.