Apple has released an update for its latest MacBook Pro systems that resolves an issue where systems running under wall power may unexpectedly shut down under heavy workload if the battery is at low levels. Apple does not specify exactly what revisions of the MacBook Pro this update is for, but it will only install on those for which it applies.
The update is a small 730KB download either from Software Update or from the Update's Web page, and requires OS X 10.6.8 or OS X 10.7.2 or later. The update will require you to restart your system, and when you do, be sure it is plugged into a reliable power source and that the battery is at least 25 percent charged to ensure it can also supply the system with ample power.
The updater will provide onscreen instructions for how to apply the update, so follow the supplied instructions carefully.
While it should not cause any problems, problems with firmware updates can result in a nonfunctional system so be sure to back up your computer fully before applying this update, preferably with a full-system backup solution like a system clone or Time Machine.