This is a simple Ruby Gem to help automate JIRA operations from Ruby. Right now the source code is in a sandbox at Apache:
http://svn.apache.org/viewcvs.cgi/maven/sandbox/issue/rissue/
You can check it out and build it yourself using Rake, or you can get the built GEM here:
http://www.codehaus.org/~jvanzyl/jiraruby-0.1.0.gem
It is still really, really rough so this is just for anyone who's interesting in messing around. Far from being production quality so caveat emptor! 
Jason van Zyl