Plugging my mp3 player into the pc is the only way I know to charge its battery.
I was transferring some photos from my phone to the pc and I noticed the battery charge indicator showing that the phone was charging. I left the phone connected and the battery charged up. Learn something every day.
I tried to test if the normal camera does the same when it is plugged into the pc, but as the battery is charged when out of unit, how can you tell? I then charged the battery normally and it seemed to charge quickly, so I am just not sure.