The latest BlackBerry OS 7.1 builds already have the awesome BlackBerry Application Resource Monitor built in. On the other hand many users still do not have it on their devices if they are sticking to official carrier builds. RIM is stepping in with a opt in program in the Beta Zone. That means you can submit your beta zone email and RIM can select you to be part of the beta. As RIM describes it “Application Resource Monitor is a service that will monitor third party applications to watch for background system resource abuse (which causes accelerated battery depletion) and will automatically close these applications.”
You can sign up to join the beta program here. Keep in mind you must have OS 7.1 installed on your device (preferably OS 184.108.40.206+) to use the application.