The bad news is that the page was eaten alive. The file was corrupted and Photoshop will no longer recognize the file format. Matt helped me find an article on the Adobe website that details the error message. Turns out my Norton Anti-virus software is a known offender and devourer of photoshop files.
I have no means of recovering this file at this time, unless someone out there knows of a means of recovering a corrupted Photoshop CS file on a Mac. I've tried file-recover before, and I've poked at the Photoshop Cache to see if I could find it in there. I wonder if it's still somewhere in the scratch disk memory... anyway.
The okay news is that I have a backup. It's several hours old, but it's not a complete loss. I also have a couple of JPG in-progress shots I was sharing with Matt, so I have a ready guide for what I had gotten done.
I will be working most of the night on this painting, but I do not anticipate it being done today. So it might be next week before the new page is up.