Yeah, see, that's where I'm confused. I can ping every other device in the list - other computers, Tivos, WD live TV - so I know that's not the problem. I know the Kindle is connected to wifi - I can use the browser to surf/download books - so I know that's not the problem. And that's where I sit. What on earth could be causing it?
ETA - FBKindle - that's what - when I stopped it (not just switched back to the Kindle framework) the ping started working.
That's where framing the question on a board like this really helps - thanks. On to the next steps.
And I'm in....