How does a view and view model get hooked up?

Take a look at App.xaml.cs, specifically at the OnImportsSatisfied method:

    public void OnImportsSatisfied()
    {
        // Add the imported resource dictionaries
        // to the application resources
        this.Resources.MergedDictionaries.Clear(); // in case of recompose
        logger.Info("Importing Styles...");
        foreach (ResourceDictionary r in Styles)
        {
            this.Resources.MergedDictionaries.Add(r);
        }
        logger.Info("Importing Views...");
        foreach (ResourceDictionary r in Views)
        {
            this.Resources.MergedDictionaries.Add(r);
        }

        if (!m_startupCommandsRun) // Don't run on recomposition
        {
            m_startupCommandsRun = true;
            // Run all the startup commands
            IList<IExecutableCommand> commands = ExtensionService.Sort(StartupCommands);
            foreach (IExecutableCommand cmd in commands)
            {
                logger.Info("Running startup command " + cmd.ID + "...");
                try
                {
                    cmd.Run();
                }
                catch (Exception ex)
                {
                    logger.Error("Exception while running command " + cmd.ID, ex);
                } 
                logger.Info("Startup command " + cmd.ID + " completed.");
            }
        }
    }

This is from the "Host" assembly. It imports the Styles and Views, and it adds them to the application resources. From that point, WPF takes care of applying Views to ViewModels because each View is a DataTemplate where the DataType is the ViewModel type itself. Anywhere WPF sees a ViewModel in the visual tree, it automatically applies the applicable DataTemplate.