WPF MVVM Samples with Database

you could have a look at those:

http://www.codeproject.com/KB/WPF/WPF_MVVM_DB_Access.aspx

or just this:

http://www.google.com/search?q=mvvm+database

The BookLibrary (WPF MVVM) sample application of the WPF Application Framework (WAF) uses the Entity Framework in combination with a SQL CE database.