Amazon just released Kindle for PC . Mac version coming soon. No Kindle required - Perfect for the netbook or laptop traveler!

I downloaded it on my iMac and it runs fine under Parallels Desktop. You can access and download the archive of books you've purchased, but not your existing "samples". When you go to the Kindle store to download a new sample it asks you where you want it sent, to your Kindle or Kindle for PC.

I just downloaded the book I am currently reading and when I opened it my current place came up and it will sync automatically with your Kindle if you alternate using your computer and kindle. I'll have to test that. Also, you can see your notes and annotations on the side, which is a nice feature.