Even when certs 'expired', I was always of the position, either when applying for work, or looking at a candidates resume, that the cert, was you got it, was yours, and nobody could take it away from you. Sure, they can come out with new editions of the technology, but if you got certified on Java 1.1, then you were certified on Java 1.1. Just my take on it though.
Here's the real deal from Sun:
What is Sun's new Certification Policy?
Beginning with all Sun certification exams taken on or after August 1, 2003, certification offerings from Sun no longer have an expiration date. Rather, certification offerings are based on a version of technology. The certification date and exam version will appear on both a certificate and an identification card with the applicable certification title.
Recertification is no longer required to maintain one's status as a certified professional. Sun certification is now directly associated with a version of technology. Nevertheless, Sun highly recommends that you remain certified at the most current technology version.