So far it looks like Facebook uploads get the iPhoto title but not the description. Pictures are tagged with the Name chosen for the Face, unless the email address is recognized in which case it is tagged with the user's Facebook name. The full name is ignored. I was expecting it to use Full Name if available or just Name if not, so I created my Names as more of nicknames.
The Flickr uploads get the iPhoto title and description, but lose the Face tagging. They do retain the Places mapping though which the Facebook uploads lack. The Flickr description does end up including the markup code that the html export plugin I use expects so the description isn't as clean as it could be.