If you get weird errors then your normal (i.e. using the ruby implementation in c) ruby program tries to access a DRb resource shared from a DRb server running on jruby try to upgrade to the latest jruby release.
I got very mysterious errors with jruby 0.9.8 but the errors went away after I upgraded to the 1.0 release.
Oh, and furthermore don’t test your DRb stuff with a method named ‘test’. It will work with normal ruby but with jruby you’ll get a ‘trying to access private method’ error. It seems like jruby defines a private test method on objects for some reason and you end up with a conflict.