I've felt for some time now that enterprises of all sizes can benefit by outsourcing many of their information technology needs to Internet-based services. The rise of powerful web-based applications shows that this vision is within the realm of possibility. Using Google as just one example, their mail and calendar applications seem quite capable of meeting the enterprise's needs--at a much reduced cost.
An article from Sun entitled Preparing for the End of IT as We Know It makes the case much more eloquently than I could have: "We at Sun have concluded that the time is fast approaching when competitive enterprises will move to a model where they run secure, network-based services instead of their own applications, datacenters, and networks."
(Thanks to Mathew Eszenyi for the link!)