The goal of the project is to allow Drew to produce real-time overlays of Vim commands. Plain English descriptions of commands, alongside the original input, would be extremely useful for teaching Vim on screencasts and workshops.
Drew experimented with various parsing solutions and eventually settled on a Ragel-based parser. This is the same approach used by some well-known Ruby projects, like hpricot. Drew is presenting a talk based on this experience called Modelling State Machines with Ragel at Eurucamp in August.