I've noticed that with the tablet docked my battery monitor numbers make no sence. I suspect the fact that tablet goes in and out of charge state is the reason.
Anyway, when trying for example OpenGarden to connect to my phone, and then giving up and packing it up, I notice 4 hours later it has used 60% of the doc, and 20% of the tablet (80% left on tab, 40% on doc) and they were both fully charged before I started.
Something seems to hang/be left behind and the tablet got very warm. Warmer than my looped antutu tests infact.
Smells like the basic idea of android is to blame here. I really wish they'd just nix that and let me choose between going back out of a program and closing it. Much faster and easier way to make sure what you want is running and not everything else.