Not much. [DEV] Current Progress and Guides - xda-developers ... Good summary. Android Development - xda-developers Discussion of details that are summarized in first link. Kindle Fire has been rooted, but it has less ram (512, vs 1,000) and no sdcard and users report it isn't as smooth as NT. Source has been released from B&N so might shed some help with root/roming. Apparent locked bootloader isn't going to help with rom development.