From the Kevin's Book : "What is .NET? Originally, Microsoft pitched .NET as, “a platform for building, deploying, running, integrating, and consuming Web services”. The result was most people thought you could only use .NET to build Web applications. In addition, because Web services were slow to catch on, it caused a number of developers to take a wait-and-see approach. You can compare this to marketing Visual FoxPro only for its Web services capabilities—although you can build Web services with VFP, it is certainly not its primary function.
After several months Microsoft recognized its marketing error and in August of 2002, Bill Gates provided an updated definition of .NET: “.NET is software to connect information, people, systems, and devices.” I think this message is better, but I’m not sure it’s clear or specific enough. I think a better explanation—at least from a developer’s perspective—is that .NET is Microsoft’s new programming model for building desktop, mobile, and Web-based applications.