further info , based on quick tests performed right now!-
charging from a PC usb port, govnah actually shows me a 'not-too-bad' positive charge current of ~300ma with the screen off. but with a 6600mah battery, it's going to take a good long time to charge a near-dead battery (ie, ~22 hours). is that what we mean by trickle charging?
with the screen on at a mid-range brightness, connected only to usb and otherwise not doing much, I saw a negative battery current of ~100ma. so that tells us the touchpad power circuits are willing to draw ~400ma from a USB port rated for 500ma, a reasonable margin of safety. (edit: oops, left out a line... I meant to say that govnah shows the touchpad draws ~500ma from the battery while not plugged in with the screen on and 100ma while plugged in to usb; that's what yields the ~400ma figure for power draw from a usb port)
moving on to the 1 amp charger scenario, with the screen off I'm seeing ~800ma of positive charge current. pretty decent actually, more than I was surmising in my post above. given that when idle the rest of the touchpad appears to draw in the neighborhood of 100ma, that means the touchpad power circuitry draws ~900ma from a 1 amp charger... again a reasonable margin of safety. this means a 1 amp charger will charge our hypothetical near-dead touchpad battery with the screen off in about 8 hours.
with the screen on at normal brightness but otherwise reasonably idle, the positive charge current on a 1 amp charger is ~330ma, about the same as screen-off on the usb port (500ma) charger.
the 1 amp charger results aren't bad at all really. this despite the "device may not charge" warning from webOS, and the absence of a battery charge indicator. even while playing a 3d game, I think a 1 amp charger could provide power at least equal to the power draw and probably just a little positive charge current (no I didn't test it and am not so inclined) (edit: actually that might not be true. I don't think the touchpad could last 6 hours on battery only playing a 3d game, which given the usuable power of the 6600mah battery implies a current draw of over 1A in that scenario... so even a 1 amp charger couldn't quite keep up in the extreme scenario of continuous 3d game play, but it'd be close!)
I don't happen to have handy a 500ma charger (ie, one that provides 5 volts on the power lines but leaves the data lines open), but I suspect that webOS provides the exact same "device may not charge" warning for it. that warning is quite correct for a 500ma charger.
It would have been nice if HP made the warning for the 1 amp charger "device will charge slowly" and would still show the charge indicator (perhaps a different color to signify the slower charge rate).
I do not believe for a moment that the touchpad will charge any differently running Android. I doubt the OS has any control over these aspects of the charging circuitry, and even if it does webOS is already drawing 80% to 90% of the available current from a USB port or 1 amp charger. you may think android quite wonderful with it's 6-digit app count, but there's no app for changing the laws of physics.