What exactly is improved in MVC3 pertaining to validation?

Question

In asp.net-mvc-3 - Improved model validation with unobtrusive JavaScript and jQuery support.

I think, unobtrusive-validation is already present in asp.net-mvc-2

Answer 1

I think, unobtrusive-validation is already present in asp.net-mvc-2

Ah no, it wasn't.

Question : What exactly is improved in MVC3 pertaining to client validation?

The Ajax.* helpers are now using HTML5 data-* attributes which are interpreted by the jquery unobtrusive validation scripts. In ASP.NET MVC 2 the Ajax.* helpers were polluting the HTML with javascript calling to the absolute legacy Microsoft*.js scripts.