As prescribed by Yahoo!, gzip\'ng files would make your websites load faster. The problem? I don\'t know how :p
Jetty will look for gzip'd versions of static files, as well as it has a GzipFilter for dynamic content.
You could probably pull the GzipFilter over into Tomcat if you wanted more control over compression than just Tomcat's connector-level compression...
http://docs.codehaus.org/display/JETTY/GZIP+Compression