Assuming the code you've put into your jar files uses Java's own classes
for time zone related activities, then using a newer JRE which handles
the new rules is sufficient.

= Steve =

My only addition to Steve W. Jackson's response is this:

If replacing an entire JRE is difficult or impossible in your
environment, you can use the tzupdater tool to update your JRE
in-place...you don't have to download an entire JRE to update the time
zone data. Of course, by downloading the new JRE, you get other fixes
too though. :)

More information about the time zone updates and the tzupdater tool:
http://java.sun.com/developer/technicalArticles/Intl/USDST/
http://java.sun.com/developer/technicalArticles/Intl/AusTimeZone/
http://java.sun.com/developer/technicalArticles/Intl/USDST/westaustralia06.html
http://java.sun.com/javase/tzupdater_README.html

Regards,
John O'Conner