Nginx and PHP, subdirectories not working

[copb.phoenix at gmail.com]

Hello list! Joined to post this but I'll be idle.

I'm having problems with my setup for a server (Lucid x86). Because
it's personal, I keep everything under the same root. I'm trying to
get it to where I can run mediawiki, but I can't get php files to work
in subdirectories. That is, with my root as /var/www,
/var/www/test.php works fine but not /var/www/wiki/test.php

My config file for nginx is posted, with changed extension, at:
http://copb.sleepingwolf.net/roots/shared/nginxconfig.txt

Likewise, the server config at:
http://copb.sleepingwolf.net/roots/shared/serverconfig.txt

Anyone have any advice on how to fix the problem? Reading files from
all over the web and the wiki have me at my wits end ~ I have php5-fpm
installed, for what it's worth... and, likewise, for example's sake:

http://copb.sleepingwolf.net/phpcheck.php
versus
http://copb.sleepingwolf.net/nginx-default/phpcheck.php

I assure you - the file is there in both cases, has the exact same
permission settings at both directory and file level, and is exactly
the same function call (phpinfo).

Thanks in advance,
~James