I reviewed your patch, and am +1 for you to commit it. That said, I wanted to clarify my proposal. My proposal is that we get rid of the $NUTCH/lib directory in its entirety, I wasn't so much as commenting on the plugin jars, though now that you bring it up, maybe we could integrate ivy in them as well. I don't think it would be too super hard to get the jars into Maven central. I'm reading up on the Sonatype Forge right now and might be able to get this working.
As for Hadoop, is there any requirement that we manage the jar lib for Hadoop in Nutch? Couldn't we simply pull the jar down dynamically via ivy or via some magic in build.xml? I think if we could then we could simply remove $NUTCH/lib whic was my original intention.
In the meanwhile, I'll create another issue to track all this, but you have my +1 to commit your patch and mark this issue as resolved. I'll link the new issue I create back to this one to indicate their relationship to one another.