Heh, heh... Web app 'designers' are learning about the Web the hard way. Client apps that pre-fetch pages will trigger poorly design apps that 'delete' via a GET. And Google release a Web 'accelerator' that pre-fetches pages. And pages from those apps are mysteriously disappearing. Convenience over correctness will bite you every time.
Google Web Accelerator: Hey, not so fast - an alert for web app designers - Signal vs. Noise (by 37signals)