No. It’s just some libraries that allow you to write Cucumber step definitions in several JVM languages so you don’t have to use Ruby. Cuke4Duke depends on JRuby and the cucumber gem.
You don’t have to do a full JRuby install unless you want to use the cuke4duke Command Line. However you will need a JRuby jar file on your file system. It can sit in a local Maven repository, or it can be a jar file you reference from your Ant build script.
Yes, you have to install the cuke4duke ruby gem. Cuke4Duke has first class Maven and Ant support, so the installation is easy even if you are not familiar with JRuby or Ruby gems. The cuke4duke gem will end up next to your JRuby jar file.