While Amazon continues to drag its feet on the Kindle version, Barnes and Noble has Why We Love Sociopaths available for the Nook. (There are free Nook apps available for Android and Apple devices, as well as PCs and Macs.)
There is no way for outsiders to know when Amazon will release the Kindle edition — it’s an unknowable mystery. One day, it will simply be there. I’m checking every morning and will let you know.
So as not to waste a valuable comment thread, I’ll share with you a thought that’s occurred to me: I’ve been reading more PDFs of late, and perhaps it wouldn’t be too extravagant to get a Kindle. The ability to stockpile Guttenberg Project texts for easy reference during class also appeals to me.
An und für sich 
The true killer app would be the equivalent to a local mirror of Perseus.
If you want a Kindle for pdfs, make sure you get the over-sized model. The original one (which, alas, is what I have), requires you to either zoom in on the text, which is highly irritating, or convert the format, which is hit or miss (mostly miss) quality-wise.
The true killer app would be the equivalent to a local mirror of Perseus.
Prester John’s mirror would be useful too.
the Kindle 4 model (nontouch) is what I have, and it reads pdfs effortlessly. The upgrade from the old is that after switching to landscape mode, it does away with margins and fits the width of the text to the screen.