ASP.NET MVC using Repository pattern - code review
You code shows not only your definition of your repository but also it's usage.

What worries me is that i don't see how the DbContext (AddressBookDB in this case) is disposed off.

I think i'd rather pass in the AddressBookDB object as a paramter to the repository constructor for usage so you can ensure it is diposed off properly by creating it in a using block.