Apple obviously couldn't figure out how to combat the issue where you're plugged into a wall/usb port for charging, still drains faster than the phone can charge. I'm watching right now after every 10 minutes or so i'm losing another 1% battery life while being tethered. Same issue that the 3G had.. It was said that the charging circuit gets shut down when temperatures of the iPhone reach a certain point (due to the 3g chip warming things up im sure) so I guess they dropped the ball for people who actually are willing to pay to tether but eventually their iPhones will shutdown on them from lack of battery life, interrupting their internet sessions. This will tell me you can't charge and use GPS at the same time either - the same problem will occur as the GPS chip heats the iPhone up about the same as 3g. Edit: Also, you can tell your iPhone isn't charging anymore when the charging icon turns to the "Plug" instead of the "Lightning Bolt" graphic.. then it's just draining.. Pretty bad Apple, pretty bad.