I finally figured out at least part of the problem after I posted from this thread:
http://forum.ppcgeeks.com/titan-upgr...r-upgrade.html
This issue is not mentioned in the howto at:
http://forum.ppcgeeks.com/titan-upgr...upgrading.html
But is mentioned, in post 5, here:
http://forum.ppcgeeks.com/titan-upgr...r-own-rom.html
If you're on PagePlus, I don't think Verizon support will have anything to do with you and PagePlus will just say it's an unsupported device, so even if getting a new A_KEY would work, you can't do it. Removing the ESN from the system and then restoring it (as PagePlusDirect did for me) fixes it; you should also be able to swap ESN to another phone, if you have one, and back (assuming you care what # is on which phone), based on what I've read.
EDIT: While SMS didn't seem to work last night, magically fixed now with no further intervention.