There is a parameter which allows "test" scope dependencies to be added to the Jetty classpath. "Provided" scope dependencies are always ignored. This is an annoyance if you wish to exlcude dependencies from the projects WAR but still have them on the classpath when testing with Jetty.
I have attached a patch which adds a parameter <useProvidedClasspath> to allow this. This was made against the current trunk, but tested with Jetty 6.1.5 as the parent POM as I am unable to compile 6.1-SNAPSHOT of Jetty due to the Glassfish CVS being down (which a checkout of seems to be required at some stage).