CRM 2011 - Instantiating the CRM Service and Impersonating it

 The below code can be used to create the CRM service in CRM 2011 and also to impersonate the CRM service

public static IOrganizationService Service() 
{
    ClientCredentials Credentials = new ClientCredentials(); 
    Credentials.Windows.ClientCredential.UserName ="Impersonating User ID Name"; 
    Credentials.Windows.ClientCredential.Password ="Impersonating User ID password"; 

    //Update the below URL as per your environment
    Uri OrganizationUri = new Uri("http://serverName/OrganizationName/XRMServices/2011/Organization.svc"); 
    Uri HomeRealmUri = null; 

    //Get the CRM Service from the CRM Service Proxy
    using (OrganizationServiceProxy serviceProxy = new OrganizationServiceProxy(OrganizationUri, HomeRealmUri, Credentials, null)) 
    {
        IOrganizationService service = (IOrganizationService)serviceProxy; 
        return service; 
    }
}