JRuby and Rails in the Enterprise

At work, management is finally getting the message about dynamic languages like Ruby and starting to recognize that frameworks like Rails may have productivity benefits.  We're actually going to look at doing a pilot project.  I like to think that I've had some influence in that but you never know...

Anyway, I would love to make this work but this is a Java shop through and through.  We can only deploy to a Java web container, specifically Weblogic 8.1 (the transition to Weblogic 10 is happening but it's months away).  I've used JRuby (works great BTW) and the JRuby extras to help me deploy an app to Tomcat, but I can't manage to get JRuby and Rails working in Weblogic 8.1.  Any ideas?

Secondly, Groovy and Grails is the other contender.  I like the idea behind Groovy and Grails but I can't help feel that it's a pale imitation of Ruby and Rails.  Anybody have enough experience to compare and share?

Finally, I'm not naive enough to think that this will cure all the ills of working in the "big enterprise".  When I think about all the things that bug me, the technology is probably the smallest thing that causes me pain.  But on the other hand, this would be a wonderful distraction. :-)