I think the only thing Amazon won't/can't do is upset AT&T, I mean by: congesting its network with Kindle traffic* AND draining paying customers with Kindle's free 3G. This is the same sort of thing that Apple goes through in restricting the iPhone's webcam action to WiFi... If it worked over 3G, everybody and their grandma's dog would be making video calls instead of voice calls**, bringing AT&T's network to its knees in 5 seconds.
* I realized something fascinating yesterday: we owe the Kindle's free 3G to the slow refresh of eInk! If the screen were fast enough to watch videos, AT&T would never allow all that free bandwidth. So the slow refresh is a blessing in disguise!
** Yes, most people think they're worth looking at. Nevermind that most are not even worth listening to! :-)
You can get a glimpse of Amazon needing to keep AT&T happy in the *first* restriction under "Developer Guidelines" on the KDK page*: No VOIP!! :-)
*
www.amazon.com/kdk/
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Yes, I love the KDK being out there. I hope a better PDF viewer is released ASAP, although it's *wonderful* that we have one at all now (in fact it's one of the two main reasons I bought the thing).
hhp