If you are new to SiteMesh browse over to Getting Started with SiteMesh which explains how to setup SiteMesh in your web application.
SiteMesh 3 is in the works. Please try it out and provide feedback.
Current Stable Release
Still to compile but you can do it compile yourself from source from GitHub.
sitemesh-example.war - a pre-packaged web project with many examples of SiteMesh in action.