My keyboard died, but came back to life. The secret was re-attaching the PDA stand.
This folding keyboard from ThinkOutside (iGo Mobility) is great, particularly with the Nokia N800 Internet Tablet. I had been using it for about six weeks, and finally detached the PDA stand, per the documentation, just a few days ago. Unit worked fine for a few days, then one day during a session it just became unresponsive... no keystrokes, no blinking green Bluetooth light, nada.
My best guess is that it's a subtle alignment issue in the plastic battery case. I've already entered and resolved an issue with ThinkOutside support. But I still wanted to lard this entry up with search terms, in case anyone has similar problems in the future, and tries to research it on the Web.
By the way, the N800 is currently just under $250 US... with keyboard, 16GB good storage, and an Apple Express you can get equipped for about $500. Can't beat it, particularly if you're a touch typist! I'm hoping the new 2008 OS has a more stable browser than the Opera in my OS 2007 (I do push browsers hard), and I wish there were an easy transfer method for a digital camera audio/video recorder. When I return from this long trip I want to research hacking the N800... maemo.org and related sites have a lot of exciting activity these days.