I use a couple of the dual battery widgets (still haven't decided on one). I sent my dock in for repair on the drainage issue a couple weeks ago. Since getting it back I have noticed that when I wake the tablet up, it can take a long time (Sometimes up to ~5-10 minutes for the dock battery to show the correct voltage). I had upgraded to 3.2 while the dock was out for repair, so don't know if its something with the new dock hardware, or a 3.2 issue.
The other day had the dock reading 0 and even after an hour of use, never did show it had a charge. Thought I was screwed because I had read several threads that said if you ran the dock down to 0, they couldn't ever get it to charge again. Plugged it in overnight and let it set, fired it up the next morning and both were at 95+%.