You have good eyes, sirbruce.
Alas, I still couldn't find anything. What's strange is that both, Kindle 1 and Kindle 2, had their FCC ID written in the user guide.
Kindle 1: UUU-L7E20070323
Kindle 2: WI5-1210
But nothing in the Kindle DX guide so far...
Btw, Amazon uses Delaware shell companies for their registrations... just to let you know.