Can someone point me to a web listing or tutorial / video that explains this new namespace and how can I use it to validate data such as user input?
Try this (sorry, not visually):
ASP.NET MVC Tip # 43 - Use data annotation validators :
In this tip, I demonstrate how to take advantage of validators from the System.ComponentModel.DataAnnotations namespace in an MVC application. You can use these validators to validate form data before submitting form data to databases.