RIM has announced that they are adding an Application Resource Monitor to OS 7.1. Much like other system features that are integrated into the OS, the new monitor keeps track of "system resource abuse" that could negatively influence battery life and automatically shut them down.
BlackBerry Application Resource Monitor monitors applications when they are in the background (with the screen on or off) and when in the foreground when the screen is off. When the app is in one of these two states, it looks for excessive background wakeups (any sort of timers firing including rapid/constant repaints) and high CPU utilization.
Overall a pretty cool feature that should help lots of users pick up some extra battery life. You can read more about the features of the Application Resource Monitor over at the BlackBerry Developer Blog. Look for it in upcoming releases of OS 7.1.