So I took an AppleScript that Apple provides for iPhoto and modified it to batch copy the Description field into the Name field in iPhoto. Compile the AppleScript in Script Editor, select a bunch of photos in iPhoto, then click Run in Script Editor. After a little bit, it should do everything. Then you're ready for iWeb!
I did this album by album in case something went wrong, but it never did. Also, I tried it in iPhoto '08, but my guess is it works in older iPhoto versions as well.

