Two years ago I had some thoughts on background applications that might police applications running on the phone. I mentioned this again within the context of the iPhone and more recently within the context of Symbian Signing.
I am pleased to see that the latest version of Android (Donut) includes a battery meter tool that shows which applications are using the most power. This is a similar idea to the Nokia add-on energy profiler.
I still think a lot more could be done to police applications on the phone. Some platforms have some user driven permissions and controls (I particularly like the BlackBerry and Android models) but none of them go deep enough to delegate full and wider control to the user.