Sometimes it really isn't the language/framework you know and really is just being a good fit with the team and being able to hit the ground running, especially in more junior positions. Personally I have my largest skills set in Rails, and when I was job hunting I ended up getting 2 offers because of free books I am working on (on Clojure and Meteor.js). One ran Rails, the other did a little bit of old LAMP stack stuff and a lot of Python and Java. I ended up taking a job working with Rails, but the road was largely paved by accomplishments that lie outside that general ecosystem.

Obviously every situation is unique, and my story may not be that of many others. I've no metrics on it. But in my experience, it largely is enthusiasm and willingness to learn over having a specific ability with someone's specific box of tools. Jormundir gave a lot of great input on what to get into depending on what sector of business you want to break into.