I got the "critter" pathfinding and basic state-machine done this weekend.
It handles a randomly-generated world (not that I have anything interesting there, yet, other than a basic maze generator to make sure they actually work), steers the critters, allows for orders to be given to critters from outside the critter (to generate "intelligent" behaviors, reactive stuff), etc. The critters aren't "smart" and are a the "programmer-art" stage graphically, but they can all independently pathfind and do motion planning in a fairly large world and all that important stuff.
Next up is probably building the world; I'm looking at various methods of generation. Thus far, the most-attractive system I've seen is to build a simplistic level-editor where I (or others) can hand-build some content, export it to a text-file, then have the game read it and plug it into other areas via <some method>. So, first off, I need to build the <some method>, then build the level-editor, then <fingers crossed> combine them.
I think that was one of the most ingenious things about Teleglitch; it combined hand-built content with randomization, for the best of both worlds.