Are you using the Microsoft JVM? If you should know that (the quote below is from here)......

In a settlement agreement reached in January 2001 to resolve a dispute over Microsoft's distribution of its Java implementation, Sun and Microsoft agreed to limit the duration of Microsoft's use of Sun's source code and compatibility test suites to support the MSJVM. Because some developers and enterprises have expressed concern about their ability to eliminate dependencies on the MSJVM in the time period originally provided, Sun and Microsoft have agreed to a longer period to permit a smooth transition from the MSJVM.

The new extension allows Microsoft to support the JVM until September 30th, 2004. You should be thinking about whether or not you need to migrate from the Microsoft JVM. There is a great transition FAQ and transition guide available on the microsoft website. There is also the Diagnostic Tool for the Microsoft JVM that will help you identify if your applications have dependencies on the Microsoft JVM. You should also begin to identify any 3rd party applications you own that may have dependencies. Many of the vendors are working on mitigation strategies so you should contact them to stay in the loop.