Actually this isn't really news. Any techie who's worth their salt has been following Google and their new develpments. Google has, for some time now, been essentially "caching" a great many things - eg Usenet posts. It's relatively simple to have a post removed from their archive if you posted it, however if someone else creates a post with, say, your name/information, you're outta luck. They won't remove it until the original poster requests it.
Now with Google Accelerator, they are cacheing web pages as well. I use it frequently, and so far, it has been great, especially at work where I am constantly using web applications and web-based informational services (directories, etc). I have heard stories of people using Google Accelerator who browsed to a forum, only to discover they have been auto-logged in as someone else - the only explanation being, Google cached someone elses credentials/cookies and the accelerator sent it to another user on the same site. So far I have not seen any anomalies whatsoever, but I guess the possibility for error exists.
Have patience with Google - they are leading edge, and thus are ironing out their own wrinkles.