In response to the new caching techniques Jennifer reported last week, Matt Cutts posted a more detailed explanation of what is called "crawl caching proxy." In short, Google may use all of its spiders, GoogleBot (Web search spider), AdSense spider, News spider, blog search spider and so on for caching purpose. So when all of these spiders crawl your pages, they are stored in what is called a "crawl caching proxy." The "crawl caching proxy" is then used for retrieving a page's cache. My understanding is that when you conduct a search at Google.com, you may see a cache retrieved by the AdSense bot, from within the "crawl caching proxy."
The Original Search Marketing Event is Back!
SES Denver (Oct 16) offers an intense day of learning all the critical aspects of search engine optimization (SEO) and paid search advertising (PPC). The mission of SES remains the same as it did from the start - to help you master being found on search engines. Early Bird rates extended through Sept 19. Register today!