Amazon can do a lot of money only from selling kindle, like Apple does with the iPod.
Use Mobipocket software to convert PDFs to that format so you can read them on Kindle.
The Kindle is already able to read more than just Amazon DRMed content, it can handle a number of formats.
Kindles can read a variety of non-proprietary, non-DRM'ed formats. They read TXT, HTML, JPEG, and non-DRM Mobi files directly.
A revolutionary portable reader that wirelessly downloads books, newspapers, magazines and blogs to a crisp, high-resolution electronic paper display that looks and reads like real paper, even in bright sunlight.