To confirm what SpideMat is saying, _some_ of my .mobi books with DRM removed on my new Kindle 3 will sync with my old Kindle (which has original books downloaded from the Kindle Store):
https://www.mobileread.com/forums/showthread.php?t=96834
*If* the ASIN is what they're tracking and we can figure out what the other part is, we can enjoy all the benefits of Whispernet between devices.
Is there a program I should be using to look at the specs on each book so I can see what the sync-able books have in common?