Is this really a problem so that you can't go on? The installer brings this message if the postgres support isn't available on your system. Isn't there a message like this some lines further?
Yes it is a problem because even if the ezpublish setup finds that there is mysql running it can't see the ezpublish database I previosly created.
I'm not runnig postgresql because I'm more familiar whit mysql.
I did this befor on Debian Woody and the early release of Debian Sarge without a problem. Thats why I'm confused now.
Hm, I have a similar installation with debian. Have you installed phpmyadmin or something else using a database? So you could test if other applications can connect mysql correctly. There have been some issues with a changed mysql protocoll (but I don't know in deep).