Last year, Google said that more than five million businesses have "gone Google". Google hasn't said how many users that entails (although over 425 million users use Gmail, so it's less than that).
A Wired study also reveals that most Google Apps users derive from a small number of domains, implying that major companies lead the charge. It's hard to believe that those corporations are stuck on Vista.
Nevertheless, if you or your business is one of the few still running a hybrid Vista/Google Apps environment, you need to prepare for change, pronto.
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