TechCrunch reports that a Kindle app is coming to Android devices sometime this summer. It will require version 1.6 or later and an SD card, and will offer many of the same features as the other Kindle apps—instant download of books and free samples from Amazon as long as you have a working net connection, Whispersync to keep your reading place synchronized across multiple devices, and so on.
Like other Kindle apps, it will not support newspapers, magazines, and blogs. However, unlike the Kindle apps for iPhone and iPad, it will allow purchasing books directly from Amazon without leaving the app itself.
For (a little) more information, see the Amazon page for the Android Kindle app.