Some caustic short answers might be:
- Yet another renaming/repackaging of OLE/COM/ActiveX/DCOM//MTS technology
- Yet another attempt to usurp a well established technology, change it slightly and then relaunch as their own revolutionary breakthrough (this time it is J2EE, XML and their all too numerous relatives, in particular EJB and SOAP/UDDI)
- Nobody knows yet, the least of all Gates, Allen, Balmer..., but it sounds cool
OK, seriously (though above answers have more than a grain of thuth in them): a new platform/architecture for development and deployment of multi-tier distributed applications (those where tasks like presentation, business logic, persistent data access etc are handled by various communicating components usually running on different machines - something like very generalised client/server concept). The architecture has many elements (e.g. lots of protocols (discovery, messaging, procedure/method invoking, authentication, transaction handling), servers - those that provide execution environment for components and others etc). The most 'visible' element is C# - a new Java-like language - and its abstract virtual machine, which is supposed to become computing substrate for all .NET components to run on.
I doubt this was of much use, but there's quite a number of Windows guys around here who will able to be more helpful
Cheers!