With the 2.0 official OS I used to get a white overlay on the battery icon (not the lightening bolt) when plugged into the PC, and under use the battery would drain, but probably less than without it plugged in; and when the screen was turned off it would actually charge, but very slowly.
With OS 2.1, I no longer get the white overlay when plugging into the PC, the battery icon just stays exactly as it is; however the performance appears to be exactly the same. I just turned off the screen for about 5 minutes by tapping the power button and battery capacity went up by 1% [confirmed, did it for another 5 mins and another 1% gain], so it still appears to slowly charge even though the indicator is not there anymore.
Cheers
The REAL Joe