So, Matchbone is coded... whether it will ever see the light of day in an official release remains to be seen. Action Baking is coded also. Apparently the Orange studio has been using binaries provided by myself and others to use the feature, though actual patch languishes in the patch tracker, awaiting review by the main Blender coding team. I'm guessing that feature will make it into official release, although it may be heavily recoded by people more skilled and knowledgable by myself.
As I've considered the character animation challenges of BlenderPeople over the last few weeks, I've come to see the need for one more addition to Blender itself: stride support. Yes, Blender has limited stride support for walking along regular surfaces when using Path animation. But that is very restrictive, and not the most intuitive method of producing walking animation. It also requires tweaking (impossible without Action Baking) to make it look less repetitive. It's less than an ideal solution.
The other way to do something like BlenderPeople, and my original plan, is to simply use fractional repeats in NLA in conjunction with preset walkcycle Actions. This would work to a certain degree, but would call for extremely careful and restrictive creation of the initial Action, as feet would have to move at a constant rate, which is almost impossible to achieve. Even if that were done, Actors sometimes move sideways or even backwards to their orientation, which would be entirely unsupported by either StrideBones or simple NLA work.
Here's my proposal: a new kind of Action Strip, called a Walk Strip. Walk Strips are not associated with an Action, though. They create one. You add a Walk Strip, fill out the parameter panel with the appropriate bone names and values (heel and toe controllers for L and R, maximum heel heights, max forward reach, max backward reach, and max outside reach). You hit the "Walk" button on the panel and an Action is generated that has your rig walking to follow your keyframed object-level animation.
As you can set different values for left and right sides, you can make the walkcycle non-uniform. The system, as I'm designing it, is footstep-based, meaning that you could (potentially) show a visualization of the footprints and even move them around, causing the walk Action to recalculate. And in the end, you can bake the automated walkcycle Action just any other, allowing the careful refinement of the animation.
So, not like I needed it, but this my new quest. Advanced character walking tools for Blender.