I have returned to confess my sins, and post how I solved my problems, because I hate it when people don't do that.
Spock, the problem was that I made a mistake and goofed up the update. See, I don't have TWRP installed, so I can't just flash the fix zip. I extracted build.prop and moved it over manually, as I did in the last OTA. Unfortunately, I forgot to set the permissions properly! With incorrect permissions on that file, the OS would not boot and I was stuck at a black screen, and stock recovery.
I did try a factory reset because I don't really care about my install and just wanted the phone working ASAP, but interestingly (to me) the reset does not blow away system files. I wiped out my user data, but it did not touch the bad build.prop file... My situation had not improved.
I eventually figured out a solution. I I learned that I could easily flash a temporary install of TWRP via the "Awe Soft Brick Fix." With TWRP in place, I could properly flash the fix, and this restored my phone to a bootable condition.
With the user data wiped out, I decided to go ahead and install "L" anyway.
I learned some things. Haven't really done much with Android yet besides rooting for the sake of ad blocking and tethering.
Thanks for making the fix!
Here's the tool to install TWRP if anyone else finds themselves in a similar state. Note this is a temporary install, stock recovery returns at the next boot.
http://androidforums.com/awe-all-things-root/850926-fix-soft-brick-one-click-fix.html)