Ok, just an update. It isn't just lsusb. I think there's an issue with cheap powered hubs and the N800. Here's what I have to do:
1. attach hub without power, get it recognized by tablet. ("USB Hub not supported" is a weird success message)
2. attach power to hub
3. attach device to hub
4. run lsusb as root

EDIT: You gotta do it in this order, and you gotta get a message about USB Hub. My tablet reboots if I don't do it right.

This method also seems to disable all of the N8x0's auto-USB stuff (the USB icon even disappears!), so the device is connected, but you're on your command-line own!

I managed to get my wifi usb stick to come online this way.

I also managed to get a stubbornly unresponsive $6 nGear card reader to work this way. I had to go an extra step, however, since there's no auto-mounting magic once you cross the dark lsusb threshold:
And it mounted!

EDIT2: I can do this:

...swap out the card in the card reader, and then do the mount line again, and I've got the new card mounted!