JSF and Struts overlap in the user interface and form processing arenas, but JSF adds a lot of extra
functionality over and above what Struts provides in the user interface arena. This means that JSF isn't replacing Struts anytime soon,
and the two make a very powerful combination. As a matter of fact, the lead author of Struts, Craig McClanahan (who is also
one of the spec leads for JSF), has
written a library to help
you use the two together. He's also said
a lot about the subject of integration. The two make quite a powerful combination.