In trying to get the Spring/Commons-Validator integration working :x I discovered a misconception that setting up the validator-rules.xml with commons validators would automagically bind errors. They didn't. But a FieldChecks class in org.springframework.validation.commons package does (it's in the sandbox). The following validation-rules.xml entry show how to access it.
Code:
<form-validation>
  <global>

      <validator name="emailFormat"
            classname="org.springframework.validation.commons.FieldChecks"
               method="validateEmail"
         methodParams="java.lang.Object,
                       org.apache.commons.validator.ValidatorAction,
                       org.apache.commons.validator.Field,
                       org.springframework.validation.Errors"
                  msg="errors.invalid"/>
  </global>
</form-validation>
Thanks for the good work, Daniel. Hopefully, it will make it out in 1.2 final (Hint, Hint).