It probably depends a lot on where you live but Rails developers are in desperate demand in the Seattle area. If you want to be a good developer you should always be learning a new language though. Clojure and Scala, and Node.js are probably some things to be looking at if you want to do some work on the cutting edge in the near future.
As for all the .NET fanboys out there; you should realize it's perfectly reasonable to not want to learn that framework. Quality of work-life is important to a lot of us and we're not just looking for any job. Being stuck in the microsoft ecosystem can be soul crushing for a developer, it also limits your future growth into other areas. There are a lot of people who need you to be savvy in POSIX, and MS developers tend to be lost in that world.