Hibernate Validator is in an OSGi bundle in the core glassfish modules, under glassfishv3/glassfish/modules/bean-validator.jar .
As it looks like the bean-validator module is just a repackaging of hibernate validator as an OSGi bundle, you might be able to snarf the version from a recent Glassfish 3.1 build, drop it in place, and go. I haven't tested this to see, though, and I'm somewhat ignorant about OSGi, so take that idea with extreme caution.
Alternately, you may be able to check it out from a suitable tag under:
https://svn.dev.java.net/svn/glassfish-svn/trunk/external/modules/bean-validator/
in svn, build it and drop it in place.
I can't seem to find the bean-validator module in gf 3.0.1 svn (
https://svn.dev.java.net/svn/glassfish-svn/tags/3.0.1/) with a quick look around, so I *presume* it's tracked in the external modules section...
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