Cloud computing is really nothing new, but rather the ongoing evolution of Software as a Service (SaaS) or, if you go back a bit further, application service providers (ASPs) which took the baton from Internet service providers (ISPs). Hey, if you want to go for broke, you can trace cloud computing further back to pre-Internet packet switching networks like CompuServe. Just don't send me email to 76011,1362 -- my first email address on CompuServe.
We are not likely to witness a stampede to the cloud, but rather a slow migration, one service at a time. Businesses for the most part still prefer to host their own email, for instance, although the majority of consumers use cloud-based email services. Smaller businesses are more likely to give up on premise email hosting to save the expense of server infrastructure and dedicated IT staff. Large enterprises are likely to consider email important enough to maintain internally, especially where regulations and potential legal issues make it desirable. Email often contains confidential and proprietary information.
Public sector will move more slowly. Already many government agencies use hosted services such as spam filtering which are essentially cloud-based. Outward facing services could be moved to the cloud since they are already in the network DMZ.
Some government agencies will never move to the cloud. The most obvious members of this group are armed forces and the intelligence community, but health and human services, benefits payments and taxation are no more likely to jump at this chance. But this doesn't mean that cloud computing is irrelevant to them. Rather, they will be clouds of their own which exist entirely within the borders of their computer networks. They could take advantage of the scalability and performance of the latest technology without putting sensitive data beyond their walls.
I'm eagerly awaiting the briefing on the Microsoft Professional Developers conference when our team returns from Los Angeles next week.