I was considering focusing on learning RoR and looking for a work that uses those techs.
After some investigation, I decided to stay with C# .NET:
It is more requested on job positions (7 to 1 in my personal searches average).
It's been around for longer.
it has better documentation and community.
One of Ruby advantages (its amazing community gems, that allows to quickly build parts of your systems by merely putting together third party components) gets quite complicated to use and maintain in huge applications, where building and reusing your own components may become a better approach.
Rail's front end support is starting to waver.
C# .NET code is far easier to understand, debug and maintain. Although certainly not easier to learn from scratch.
Though Rails has an excellent programming speed, C# tends to get the upper hand in long term projects.
I would avise to stick to rails when building small projects, and switching to C# for more long term ones.
Opinions are welcome!