look for .evolution/addressbook. In general if you are doing an upgrade to Fedora I would backup your home folder and include all the hidden files. Then you can copy the addressbook files back over the new ones to get everything back. On my computer I backup .config .fonts .evolution .mozilla .jpilot .gnome, etc.
If you want to get a little fancy and do this automatically with something like an external USB drive for safe keeping you could use something like my backup script. I have it attached to a desktop button and I press it to trigger a backup as needed. If you want to get even fancier you could set cron to run the script each night automatically. I kind of learned this the hard way to always keep a spare copy of stuff I really want on a spare drive after losing a years worth of work, mp3s I ripped when a harddrive died on me. ouch.
# backup shell script for Mark's Fedora Box
# clear mozilla cache before copying, no point copying crud
rm -rf /home/mark/.mozilla/default/Cache/*
# touch usb drive to activate
# rsync backups only changed files, plus removes old deleted files
rsync -a --delete /home/mark/Documents/ /media/19G_Drive/Backup/Documents
rsync -a --delete /home/mark/.mozilla/ /media/19G_Drive/Backup/.mozilla
rsync -a --delete /home/mark/.jpilot/ /media/19G_Drive/Backup/.jpilot
rsync -a --delete /home/mark/.config/ /media/19G_Drive/Backup/.config
rsync -a --delete /home/mark/.gnome2/ /media/19G_Drive/Backup/.gnome2
rsync -a --delete /home/mark/.fonts/ /media/19G_Drive/Backup/.fonts
rsync -a --delete /home/mark/.openoffice.org2.0/ /media/19G_Drive/Backup/.openoffice.org2.0
rsync -a --delete /home/mark/Music/ /media/19G_Drive/Backup/Music
# notify backup is completed, fancy reminder popup
notify-send --urgency="normal" --expire-time=999999 --icon="gtk-dialog-info" "Backup Completed" "Rsync finished synchronizing the folders: Documents .mozilla .jpilot .config .gnome2 .oppenoffice and Music"