It is not harmful for the phone to remove the battery while it is on...many phones require a "battery pull" to actually reboot, using the power button basically just puts many devices in a sort of standby or sleep state, and doesn't actually turn them fully off. As joebob2000 posted in reference to his BlackBerry, the only way to TRULY turn a BlackBerry off is to remove the battery....and it doesn't matter what year device it is, either - both my ancient 8100 pearl and my Bold 9700 are that way, as well as my 8220 Pearl Flip , and the new Bold Dakota 9900.