I don't know, I err towards validation in or close to the model. You shouldn't be able to construct an invalid model and that usually involve the model validating the data you're passing to it. Rails certainly doesn't go about it in a great way though and tends to leak view based concerns into the model.
How you achieve this depends upon the language. One thing I like to do in statically typed object oriented languages is to use classes for basic data rather than spread primitives everywhere. This makes it obvious where to put validation - e.g. the PhoneNumber class in the model will necessarily ensure the data its passed isn't bad. Repeating that logic in a controller or view tends to be a poor decision.
How you achieve this depends upon the language. One thing I like to do in statically typed object oriented languages is to use classes for basic data rather than spread primitives everywhere. This makes it obvious where to put validation - e.g. the PhoneNumber class in the model will necessarily ensure the data its passed isn't bad. Repeating that logic in a controller or view tends to be a poor decision.