Well... I've seen "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" since 3rd March 2004 and "Googlebot/2.1 (+http://www.google.com/bot.html)" since 15 June 2004, so this is pretty old news.
They might get pulled from the SERPs if they are serving substantially-different content with intent to deceive, but the reason I noticed this in the first place is that one site I administrate was getting so badly abused that it is now "armored"; It won't allow access from any unrecognized user-agent. When the new Google user-agent visited, it got a 403-Forbidden.
Since it's a non-profit info site only, this is no big deal. But of course I fixed the problem by allowing the new user-agent. Googlebot came back the next day, and the site didn't suffer in the SERPs at all.
Additionally, the site *is* cloaked in that it returns a shortened, "prettier" title to search engines that do stemming for plurals like Google does. Still -- no ill effects from this situation.
Maybe this *is* old news, but I didn't see any other posts on it.