Originally the "Meet Hudson" page  had a JNLP link to run the latest version immediately. This was used in AddTestInstanceAction, making it easy to try Hudson quickly. Later this link got broken (HUDSON-8644 ) so the action was removed from HudsonRootNode in 81b3dbad05ff. (You can try the live Jenkins version at  or by running  to see how it worked.)
Would be good to resurrect this action somehow. Either pressure the Hudson team to make the JNLP link work again, or try to reimplement using a plain WAR download , which however suffers from the problem that you need to figure out where and how to cache the download and perhaps update it.
 javaws http://jenkins-ci.org/jenkins.jnlp