More brain surgery
The iPhone requires a fundamentally different approach to user interaction. Something that goes way beyond the obvious things like the multi-touch interface.
If you can have a background process running on your iPhone, what is that process going to do when it detects a state change? What happens with a buddy comes online, or a new piece of data is available, or when a long running calculation is completed?
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You’re [sic] phone soon becomes a fricken’ pinball machine as multiple applications fight for your attention. With 24 notification permutations for every application, things will quickly get out of hand.
Calendar notifications are jarring enough for me, so I’m glad that it won’t be possible for any custom applications to deliver sound notifications when I am not actively using them.