Interesting discussion on Slashdot - Who is Using Tomcat or Jetty in Production?

No one recommending Websphere, I notice.

We are using Tomcat for our latest product, but we haven't rolled out to our largest clients yet...

If we end up with scalability issues, there are some alternative J2EE servers mentioned here which we can look at.

I've been looking at JBoss anyhow. Tomcat gives you Servlets and JSPs, but not EJBs. JBoss gives you the whole J2EE stack.