It's nowhere near the same scale as cities in the US and Europe, but Wellington, New Zealand definitely has a lot of demand for Rails developers right now.
I also know of recent jobs openings in Christchurch (if you can't take the shake), Nelson, and Auckland.
I would suspect the market in Australia is hot. Sydney, Melbourne, and Brisbane probably best bets, though supposedly there is a big shortage of IT workers (haven't heard Rails specifically) out west to support the mining industry.
Australian pay is better than NZ pay due to exchange rates.
Personally, I'm looking for at least one junior level developer to work with me on projects as a freelancer. Remote from anywhere is fine as long as you have excellent English language communication skills. If you can't write and speak in English well, it's a non-starter. I expect some sort of code on github to look at too. Contact me at wm -at- waltermcginnis dot com.