Actually, ValidatingFormModel does have a member for an associated RuleSource, that can be set or retrieved via lookup (for accessing a shared instance configured in the application context, as PetClinic does). This is how form fields get attached validation policies.
With that said, I completely agree with you: we need to support more metadata, metadata driven control selection and formatting is a big thing. We should support various means of metadata specification: e.g programatically, configuration file, jdk 1.5 attribute, etc.
Good suggestions...I hope we can offer solutions here soon. I invite you to take a look at the existing PropertyAccessStrategy code and PropertyMetadataAccessStrategy code in the binding packages: that's likely the area we want to develop/enhance, in addition to the form framework. I'd be very interested in your ideas/contributions.
Core Spring Development Team