The Kindle is black and white only and does not handle PDF's well, so don't expect the Player's Handbook to be available for it immediately.
However, there's nothing stopping you from downloading the SRD as a text file and converting it to a .mobi format and transferring it to the Kindle via the USB cable. You could do that with the 3.5 SRD today, and include your house rules in it and everything.
But for the gaming table I'd rather just have a laptop. The Kindle doesn't allow me to Alt-Tab over to my spreadsheets or maps. This really is just a "reader", and not dynamic enough for the gaming table (IMO, YMMV, etc., of course). I think the best usage scenario for the Kindle is reading the newspaper on the train/bus in the morning, or reading a novel under a shade tree.
And $400 is pricey, but you actually may save money in the end if you already buy enough books / subscribe to several newspapers. The prices on the media are very competitive (e.g., $9.99 for a new book then available only in hardcover for no less than $17).