Originally Posted by John Yeoman
Problem is, if Kindle gets a lock on the market, it becomes a one-channel solution. Whatever color you want, provided it's black?
You're free to read anything you want with the Kindle in PDF, plain text or Mobipocket format. Your Sony lets you read anything you want in PDF, plain text, ePub and RTF formats. The standards documents which tell you how to create Mobipocket files and ePub files are both online and freely available without needing to agree to any contracts or NDAs.
People successfully use the Kindle without registering or even using the Kindle store so no, there is no lock on the market.