Less than a week ago, Microsoft released Windows 7 beta to the general public, and a publisher has already posted an eBook for Kindle (a somewhat short one, I’m sure). This kind of thing is exactly what Kindle is all about.
Kindle isn’t the death of books; I think Kindle is the rebirth of things like pamphlets, and, to a lesser extent, short stories (which, sadly, have almost vanished from most magazines, and exist only in journals). Physical books on Windows 7 probably won’t come out until a few months before Windows 7 retail launch, but Kindle makes it possible to get stuff like this out much earlier.
I think the thing Amazon should be investing more money in is getting well known authors to post original material on Kindle; it doesn’t have to be anything like a book. A simple essay or short story would work just fine; something that shows the world that authors are just as eager to experiment with Kindle as publishers are.