Provider Model Design Pattern

The beauty of this pattern is you can create a new class, for example, OracleForumsProvider, by deriving from the ForumsProvider base class and use Oracle as your data store. Or, if you prefer to continue using SQL Server, but wish to change the behavior of a single method, you can derive from SqlForumsProvider, override the method whose behavior you want to change, and then add that new class to the section of configuration. More simply put: the provider design allows developers to publish well-known APIs and also allows for a rich, enterprise-level extensibility model.

It is not a brand new idea; it came basically from the popular strategy pattern. It is a good idea to have a quick look at the strategy pattern in here.

MSDN
Provider-Pattern
http://www.codeproject.com/
strategy design pattern