As a test I just tried MobiDeDRM on an .azw book I bought after updating to 2.5.2, and indeed the script no longer works, with a "no key found, maybe the PID is incorrect" error. This was a book downloaded via computer for USB transfer to the Kindle in question.
I expected as much, but it's good to check these things out for oneself.
Now I can't say I won't buy
any books until this gets sorted out, but I'll certainly be buying
fewer books. Especially with the prices going up at basically the same time. I have total confidence that this is a temporary situation, but in the meantime that's an unknown number of snap purchases I won't be making. The sooner the smart script people get their hands on 2.5.x and update the tools, the better it'll be for Amazon's and the publishers' bottom lines.