In a thread that was started Feb 10 at High Rankings Forum, a member asks what is going on with the Google cache. Although Barry discussed the topic of Google Cache Currently Offline back in late January, it seems that the problem may have evolved into more than just an error page. Instead, people are seeing very old versions of their content in the cache.
Although the thread at High Rankings does drift off into a somewhat off-topic (but good) discussion about links on the second page, page 3 jumps right back into the Cache problem and has generated some good responses.
See the thread at High Rankings Forum.