I consult for a number of startups, both at seed stage and with significant revenue. Mostly I do web applications, as opposed to "sites."

I'm seeing more organizations learning towards frameworks like Ember.js and Angular.js. I'm also hearing lots of things like, "When I update the data in this browser, I want the changes to automatically propagate to other browsers."

Among other things, this means I need robust plugins like ember-rails that integrate into the asset pipeline and provide appropriate generators. I also need libraries similar to Socket.io that can notify the browsers when the model changes.

I don't necessarily want these features to be in the Rails 4.1 core. But I suspect that I'll be building more and more apps like this over the next two years, and I'd love to see Rails be a strong competitor on the back end.