Been waiting for this for a while. I requested they add a !blockchain feature a while back, but this is the first I've heard of them doing bitcoin-related dev.
I do love DDG, but I don't think it's actually the DDG team that is working on these bitcoin plugins. One of the cool thing about DDG is that anyone can make plugins. All you have to do is fork one of the DDG repositories, develop your plugin, and then submit a pull request. If you've made a good, useful plugin they might integrate it into the live search engine.