Apache JetSpeed is a servlet and thus requires a compatible servlet engine in order to run. Thus JetSpeed works with any JSDK 2.1 compliant servlet engine.
Even if Apache JetSpeed is fully compliant and therefore fully portable between different servlet environments, it has been tested only with the Java Servlet Web Development Kit. As soon as Jakarta is ready it will become JetSpeed's target platform.
Please report any success or problem with other platforms to the development mailing list.
Enjoy!