Kindle for PC offers many of the options you'll find on the hardware reader, plus full-color images in several books. Some are speculating the latter might mean that a color Kindle is on its way. You can also read notes and highlights created on your Kindle device, but you can't create them on your PC for now, nor you will be able to access blogs, newspapers or magazines from within the app -- which is not really a big deal given you'll be sitting at your computer anyway.
Windows 7 users can use multi-touch pinching gestures to zoom in, and in future releases, turn pages with finger swipes. Other upcoming features include a search function and the ability to zoom in or rotate images. Amazon's well-known brand name in the market will probably help it shift a lot of books directly to computers, we only hope they'd loosen the DRM restrictions.