So, we are going back to mainframes (sorta). First it was big computers in big rooms. Then everyone had to have their own computer. We figured out how to connect them, but the model still wasn't quite right. We've had thick clients and thin clients and problems with each. We've had shrink wrap software and online software. We've heard of Software as a Service (SaaS), but it always seemed like a dream wrought with performance and scalability problems.
The new world is Cloud Computing where the Services are hosted in scalable data warehouses. The clients follow the client hybrid approach using a technology such as Silverlight or sophisticated Ajax to consume the services and present a rich user experience. On the server side IT data center issues go away, scalability is built in, and shared resources make it greener.
Software + Services
http://msdn.microsoft.com/en-us/architecture/aa699384.aspx
SaaS Architecture
http://www.microsoft.com/feeds/msdn/en-us/architecture/media/SaaS/splusarcperspectives.asx
Live Mesh (bringing it together)
http://blogs.msdn.com/livemesh/
Microsoft Software Online
http://www.microsoft.com/presspass/press/2008/mar08/03-02AllSizeBusinessesPR.mspx
Bill talks of the Cloud (top priority)
http://www.microsoft.com/winme/0802/32460/Sharepoint_BillG_JaniceKapner.asx
Coca-Cola Online
http://online.wsj.com/article/SB120451096788306801.html?mod=rss_whats_news_technology&apl=y&r=375403
Others
Amazon EC2: http://www.amazon.com/gp/browse.html?node=201590011
Google: https://www.google.com/accounts/ServiceLogin?service=ah&continue=http://appengine.google.com/_ah/login%3Fcontinue%3Dhttp://appengine.google.com/<mpl=ae&sig=2441550b0617bb4eb9e7f8c3eb9e63b1