The reason 1.5 prints errors is that JNA was removed from JRuby. Limelight should still work, except native features like kiosk mode, despite the error. Downgrading jruby to 1.4 should get rid of that error.
If you're running off the installed version, not the gem, then you might also get a FileNotFound error when trying to open a remove production. To fix this, create the directory "<user folder>/Application Data/Limelight/Downloads" and "<user folder>/Application Data/Limelight/Productions".
Both of these annoyances will be fixed in the next release.
Development is not dead. Some major changes are underway which is why the next release has been so long in the making. Some of the new changes include,
* better performance
* more flexible Players API
* Support for Clojure productions in addition to JRuby.
Micah