Good lord slashdot, I was hoping to see informed technical discussion like that slashdot of old instead of scaremongering gossip over motives for the Book Store compatibility. It has nothing to do with Apple controlling Amazon, or browser wars. The HTML5 database storage spec is not fully standardized, and so chrome and safari both implement the WebSQL spec while Mozilla has chosen to go with their own IndexedDB spec.
The book store will be ported to firefox shortly as both DB implementations basically accomplish the same thing. It came out for Chrome and Safari first because Amazon wanted to circumvent Apple's in-app purchasing requirements on the iPad and that meant working with webkit first. Down the line I am sure that browser makers will eventually converge on either IndexedDB or WebSQL and that will become part of the HTML standard but for now the discrepancy is explainable purely in terms of using a non-standard technology that browser makers are still experimenting with and trying to shake out.