Hi friends
JSF (JavaServer Faces) is Sun's standard Java web development

technology. This technology greatly simplifies developing web applications and is well suited to create rich web applications. It is a robust component based framework, event driven programming model offering a lot of reusable UI components, extensible architecture, support for multiple client devices etc.You will need the following:JDK1.4,Tomcat 5.0 or any other servlet container (JBoss, Resin, JRun) and Ant.
I hope this information is helpful for you(This information is only for freshers).
For more detail,the links are java.sun.com/javaee/javaserverfaces/ ,en.wikipedia.org/wiki/JavaServer_Faces etc. Thanks. Deepak