The single most important messaging principle, according to marketing guru Al Ries, is to "own" a word in the customer's mind. In my mind, Google stands for "search". While I use Google Local, Gmail, and Google News, I don't speak of "googling" my maps, "googling" my e-mail, or "googling" my news. I "google" - i.e. search for - keywords.
With the proliferation of new products, Google is losing its focus. It is trying to position itself more broadly as the "world's organizer of information", but that message is not as meaningful and precise as "search".
An article from the BBC discusses this issue and hints that Google may be at its peak.