I just tried to enable UserDir configuration on Fedora 14 and it seems that it's quite different with my configuration in Slackware. Well, it's a different distribution, so i guess it's quite normal to have this small difference.
In Slackware, all i need is to remove the hash mark in front of this line: Include /etc/httpd/extra/httpd-userdir.conf in /etc/http/httpd.conf and restart Apache and it will be done.
On Fedora, it's slightly a bit different. First, you have to edit /etc/httpd/conf/httpd.conf and change this line: UserDir disabled into UserDir public_html.
Next, you have to uncomment all this section below the UserDir configuration (i added FollowSymLinks option on my case):
AllowOverride FileInfo AuthConfig Limit
Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec FollowSymLinks
<Limit GET POST OPTIONS>
Allow from all
<LimitExcept GET POST OPTIONS>
Deny from all
I added index.php on DirectoryIndex as one of the entries because i will be running PHP scripts.
The last thing that you should do is setting the permission on the /home/username to 711 and /home/username/public_html/ to 755. That should do it. Restart your Apache by issuing /etc/init.d/httpd restart and you can start accessing your script at http://localhost/~username/