You’ve been able to get Real World Haskell in a form useful on a Kindle for awhile now, from O’Reilly directly.
Now, RWH is also available for purchase for the Kindle directly from Amazon’s Kindle store — and has a new Kindle Edition page on Amazon. So if you have a Kindle, you can now purchase RWH directly from your Kindle, or have it automatically installed to your Kindle after buying it at Amazon. The Kindle Edition is currently $31.99.
The O’Reilly digital edition is, of course, still available at $39.99. Their edition gives you DRM-free files, and a single purchase gives you multiple formats: PDF, .mobi (Kindle), Sony, iPhone, etc. If you use Safari Books Online, RWH is available there too.
And of course, you can still get a shiny copy to actually sit on your desk. I have one on my desk at work, and still have to explain the beetle on the cover quite regularly. (The explanation is on page 671, right after the index).
I’m excited about the Kindle version. I’ve been reading waaaaay too much since I got my Kindle back in March. I think the Kindle DX would be especially good for a book like this, to reduce wrapping code examples and tables.