I don't really know much about MML so I'll let Steve field that part.
: My other question is about something I read on source.bungie.org long ago
: that was called "Bridges and Balconies". Apparently it was so
: revolutionary that the Nardo Group was going to put it into an all-new
: version of TI for Aleph One. So what happened to it?
Bridges and Balconies was a fork (alternate version) of Aleph that supported some types of geometry that the normal engine did not- bridges and balconies and some truly 3D elements. It would have made map design a whole different ball game if it had taken off. However, it was a real bear to work with- you had to partially finish the map in Forge and then hand-code some MML to hook up the 3D elements. I never heard anything about scenario remakes based around it, and for some reason it was never moved back to the original Aleph code, probably because it touched so many aspects of the engine and was no longer compatible with the main branch when development stopped. The only scenario I'm aware of that really makes use of it was called Muerte Machine/Carlos on the Run, and it only runs on its included custom build of Aleph which is for Mac OS 9.
: Oh, and one more thing for Mark, Steve, and Dr. Sumner regarding RED: did you
: ever find the High Velocity Sub-Orbital Pissed Off Weasel?
No, but I suspect it replaces the skull if you make or find a RED netmap and play KTMWTB.