Question: Does ASP.NET MVC provide a standard validator functionality or do you have to create your own validation manually? If the latter, is there any third party validator available that you can use on ASP.NET MVC web applications?

Answer: 
Shortly after I posted this answer I found [xval](http://xval.codeplex.com/) which is a validation framework for ASP.NET MVC.
David Hayden [wrote an article](http://codebetter.com/blogs/david.hayden/archive/2009/02/03/an-aha-moment-on-mvc-validation-extensibility-in-defaultmodelbinder-bye-to-idataerrorinfo.aspx) over at www.codebetter.com describing a great way to handle validation. Of course xVal is an option but it's always great to have an understanding.