BBM for BlackBerry 10 to use darker theme to prolong battery life
which should help extend the life of the battery because the OLED screen requires less power to display them than it does with brighter colors. We all can use longer battery life, but BlackBerry users haven't been hamstrung by the cell in their handset as much as Android users running over LTE have been. The slide from RIM indicates that switching BBM to a simple black theme can decrease battery use by 25%. Further optimization of the OLED screen that will apparently be on the new BlackBerry models, can result in a hefty 75% decrease of normal battery consumption.
If this focus on what the BlackBerry user needs for a great user experience permeates the new hardware and software, rumors of RIM's demise might have been greatly exaggerated.