This plugin makes Hudson cluster act as a Hadoop cluster without any configuration.
When you install this plugin, Hudson will start a Hadoop "master" (namenode and job tracker, in their jargons) on the Hudson master. On each slave that Hudson starts, this plugin also starts a Hadoop "slave" (datanode and task tracker, in their jargons.) Hudson then instructs Hadoop to form a cluster among those nodes. All the jar files needed to run Hadoop is packaged inside this plugin, and will be automatically deployed to eveyrwhere they are needed.
In this way, this plugin takes your machines in your Hudson cluster and runs a Hadoop cluster very easily.
Once installed, you'll see the "Hadoop" link in the Hudson top page.
Slave log page (http://yourserver/hudson/computer/SLAVENAME/log) will also include text showing how the hadoop slave JVM is launched. Any error encountered will be recorded there, too.
Once you run this, you'll get $HUDSON_HOME/hadoop/dist directory that contains the stripped down version of Hadoop. You can change conf/hadoop-site.xml in this directory to apply different parameters.