I get asked whether I know anyone who is available for Ruby gigs quite regularly - and the answer is almost always 'not at the moment' - but I'm not a definitive source! The recommendations I always have for potential Rubyist employers/clients are:
Attend a Melbourne Ruby presentations night - they're always on the last Wednesday of the month, excluding December. These are the most social events (hack nights and InstallFests are a bit more studious), so they're the best opportunity to meet Rubyists face to face. There's also the opportunity to give a short (10-30 seconds) pitch for anyone who's hiring early in the evening (but stick around after that, so people can find you and chat further!).
There are also always a few recruiters at these events - perhaps it's worth having a chat with them too? The fact that they attend events is a good sign that they're engaged with the community.
Post to the Ruby/Rails Oceania Google group about the position - but please note the job posting guidelines. I'm a moderator there too, so I'll likely be the one pointing out anything you've missed from those guidelines.
Relatively new, but it doesn't hurt to post the role here as well.
You can join the Slack group easily enough, and then share your role in the #jobs channel.
Good luck!
Pat Allan / @pat