[wp-hackers] Security issues with multi user installation

[R.J. Kaplan]

Hi,
I'm setting up a blog hosting site, and I really want the users to be  
able to use their own themes, what are the different security risks  
and implications to this?
I am NOT using mu, rather a customized WP config file that gets the  
right tables from the database based on the subdomain. currently it's  
set up that the different blogs use different tables in the same  
databse (with no shared tables) but I can seperate them to different  
databases if that helps, though the db user will still be the same.
~Joe