Do validations only allow true or false

[Guido1982]

I was asked to do a validation where the salesorder shipping address needs to match the account shipping address. Now that's easy enough, but I was also asked to provide the option to overwrite the currect salesorder address with the address from the account when there is no match. Do we have some option to fire a custom function when a validation fails or is it just true of false? And if it is, would it be a good idea to allow custom 'ontrue' and 'onfalse' handlers? I could work on that.