Well here's irony. I did not follow my own instructions and did not take a back-up of anything before running the new updater. And now my Apache config is hosed, and I am feeling rather dumb. And rather annoyed at the Adobe ColdFusion team. Or whichever of them are responsible for WSConfig, anyhow.
In my defence, I did not take a back-up because I only thought about the ColdFusion side of things, and the CF10 install on this machine is pretty fresh, and if it did happen to die, I wasn't that fussed, and I expected the updater to work. Which - from a ColdFusion perspective - it did.
Now this is where I am dumb. I was aware that when I re-ran WSConfig, it might get confused with some changes I had made to mod_jk.conf, uriworkermap.properties and workers.properties and as a part of getting multiple CF instances running different virtual hosts on Apache (thanks to Rob Brooks-Bilson's excellent article). However - foolishly as it turns out - I trusted WSConfig to back up any files it changes before making those changes. Because I knew full well that it does make a back-up of httpd.conf before it changes it. So - here's the dumb bit - I gave WSConfig the benefit of the doubt that it'd back up the other ones too and just ran it. And it overwrote all three of those files without backing them up. Amateur hour, honestly.
Still: I bring these things upon myself, I guess.
I haven't fixed it yet, but Apache doesn't start so badly that it doesn't even log why it can't start (which is a new one on me). But if I take the connector stuff out, it does start.
I'm going to raise a ticket on the Adobe bug tracker to get this fixed (3358792). WSConfig should not back-up some of the files it changes, but not the rest of them. That's dangerously misleading.
Fortunately it only took about 40min to track back what I needed to do and redo it. That's 40min of my life I won't get back though ;-)