Service virtualization is relatively new term being used in the SOA quadrant these days. 

It refers to…

•   The abstraction of where the actual service is running
• The abstraction of what protocol the service is listening in
• The policies that can be applied to an instance of a service to control auditing, security, etc.
• The provisioning of these services onto various servers located on the network
• The ability to add services dynamically or move them around without the clients of these services being affected
• The ability to add an instance of a service for a new customer as they come online and configure each instance to totally different resources (databases, etc.) as well as apply any necessary policies to fulfill obligations, etc.
• .NET 3.0 does not out of the box provide these capabilities, but does completely provide the basis for such a platform. 

Aware Server is such a platform and was built with service virtualization in mind.  The core of Aware Server is a distributed service registry allowing all services and clients the ability to find other necessary services without knowledge of where they running or what protocol they are sitting on top of. 

Developers build WCF based services inside Aware by focusing simply on the Service and Data Contracts.  They then provide the Service Contract implementations and publish their service into a centralized manifest store.

Application administrators then configure service provisioning policies that include membership conditions so your network and be virtualized depending on your needs.  All the servers will apply these policies and every node on the network will know about the registry changes immediately. 

Aware Server allows each service to publish associated attributes (name-value pairs) into the distributed service registry.  Clients and service consumers can query for specific services they are interested in. 

For example your software might be slightly customized for each client you have or each client demands their data be stored in an isolated database instance.  A developer will build the service one time and expose configuration out the service allowing the application administrator a chance at provisioning time to provide connection strings, etc.  The application administrator can also attach extra attributes to the service instance ensuring that all service requests are handled by the right service and results are put into the isolated clients database instance.