btw i am using

        if (!-e $request_filename) {
            rewrite ^.+/?(/wp-.*) $1 last;
            rewrite ^.+/?(/.*\.php)$ $1 last;
            rewrite ^(.+)$ /index.php?q=$1 last;
        }

i think you are running it all through index.php wondering if that would not cause trouble here and there?