If you have always placed a description of photos in the Description field in iPhoto instead of the Name field, then you'll be in for an unpleasant surprise when using iWeb (or the .Mac gallery). That's because when publishing photos using either method, it only gives options to display names and not descriptions underneath each photo.
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.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20070822121100394