For my part, I’ve been working on a project that is tangentially related to language workbenches.
In short, it’s a language-parametric source code index and search algorithm. I put together a prototype in python early last year, and have been working on a port to scala in my free time since then. The scala version will begin to be demo-able in the next couple of weeks. This will be followed by several months of deeper research into scalability and performance.