MCE (Mode Control Entity) is the daemon that handles display brightness, notification leds etc. via several plugins. One of the plugins, libbattery.so is responsible for enabling the BatteryCharging and BatteryFull patterns. The patch also makes it enable the BatteryLow pattern, exactly the same way as the lowbatled daemon and the original script do.
In the long term, we should (in the Community SSU) replace the whole MCE daemon with the open source version from MeeGo. Short term, I guess I could put a modified libbattery.so module in the lowbatled package instead of the daemon, if that makes any sense.