MVC 3 picks up some new, very useful validation features available due to .NET 4 support. For example:
– MVC 2’s DisplayName attribute wasn’t localizable, whereas the .NET 4 standard System.ComponentModel.DataAnnotations Display attribute is.
– ValidationAttribute was enhanced in .NET 4 to better work with the validation context for the entire model, greatly simplifying cases like validators that compare or otherwise reference two model properties.