I just ripped through the "Agile Develoment with Ruby on Rails" book. Spent some time lurking in their forums and mailing lists... And I gotta say there isn't anything in RoR that isn't borrowed from J2EE and the advantages ( and disadvantages ) that come with with weak typing. RoR is basically Tomcat, Hibernate, JUnit, Ant, and JavaDoc ( on crack ) without having to figure out that you need all these technologies, then having to download and configure them, and learning them the hard way.
The only advantage that I see in RoR is it's Evangelist community. There are some very smart, and more importantly, enthusiastic and freindly people leading the RoR community. Ruby is fun because it's advocates are fun, while Java is boaring because, well let's face it, the Java community is about as dead and dry as dirt.
A smile and a few beers could sure do alot for J2EE.
As far as Perl goes... anybody writing web apps in Perl these days really needs to rethink their strategy. Great language, but it's still pretty much WRITE ONLY.