They say that information can be stored in a single place, and made accessible through, for example, Microsoft Passport. There are many other things that they want to talk about. Please check out the Microsoft website for more information. To make a long story short, .NET is yet another attempt at a common language. Here is what Microsoft's press release had to say about Windows.
NET is the next generation of Windows.
NET will be a product that supports productivity, creativity, management, entertainment, and much more. It's designed to put users in control of their digital lives. NET will be self-supporting, featuring services that provide ongoing support and updates as users need them. NET will provide a rich foundation for developers who want to create new .NET applications and services. It will offer a programmable user experience that can be customized by corporations and individuals and programmed by .NET services, including MSN.NET, bCentral for .NET and Office.