Okay. The error went away after I uploaded the files from the wordpress root directory again, so something probably got missed on the first (and second) passes. That left me with a blank screen, which lots of people are getting.
I then logged into my admin, it prompted me to upgrade my database, which DID go smoothly (thank you WordPress, sorry for the vent earlier.) Front page remained blank until I went to the Appearance page, which told me that my selected theme was broken and was restoring to the default.
All now appears to be well. It looks like the cron.php (and update.php, if you got that one too) were the result of the root files not being copied over properly.