It seems to me that Google does not cache (all, if any) RSS feeds. When I refresh the page while watching my crawler monitor screen, I can see Googlebot quickly fetching the 'unavailable' feeds from my server. After a while they get updated on the page.
Some feeds can't be added. For example Google's news feed 'http://news.google.com/news?hl=en&ned=us&q=Google+Sitemaps&ie=UTF-8&output=rss&scoring=d' doesn't show, not even after dozens of clicks on 'Go' during the last week. The same happens every once in a while with MyYahoo too by the way. Microsoft's sandbox even likes to crash my browser, what I consider the usual behavior of MS products, sandboxed or not.
Tags: Google RSS
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