Looks like the only two really successful companies to market tablets--Apple and Amazon--by no coincidence have the capability to also provide a store with plenty of apps and media with which to populate those tablets. I doubt any other companies could compete in the tablet market with Apple and Amazon at this point, with the possible exception of Google, and even Google would be hard pressed to compete. Hats off to Amazon!
I don't consider Microsoft as a competitor as they would not release their own tablets, just the software. I do hope Windows 8 starts the transition from lackluster iOS and Android tablets to powerful workhorse tablets.