This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
I assume you are talking about distributed apps since you mention different JVMs. Static variables are local to each JVM. So you cant share data between servlets on different JVMs. If you want to share data, you might consider using sessions or other mechanisms like a DB. For the same reason, you cannot even depend on static variables for storing any data. The container might decide to migrate your session to a new jvm where you will lose all you static vars values unless you take explicit steps with the HttpSessionActivationListener interface.