Isso deve funcionar:
location / {
try_files $uri $uri/ @rules;
}
location @rules {
rewrite ^/([a-z]*)$ /index.php?action=$1;
rewrite ^/([a-z]*)/(.*)$ /index.php?action=$1&item=$2;
}
location /index.php {
fastcgi_pass 127.0.0.1:9000;
include fastcgi_params;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
}