Thanks for the response. A couple follow up questions:
(1) With the kindle 3 (wifi or 3g+wifi) why is still necessary to do the networking via usb? Why not just have a simple update payload that copies over a static ssh or telnet daemon, and starts it up. Then connect from a workstation via wifi. Or does the kindle cripple the networking over wifi? And if so, why not add some extra code in the update payload to uncripple it?
(2) "On the Kindle 3, no soldering is required any more." Really? That sounds awesome. How does that work? Does a standard usb-rs232 cable work or something like that?