Anyway, as of the release of Plesk 11.5, it is now possible to swap out MySQL server for Percona and MariaDB.
I've put a guide together here: http://xenforo.com/community/resources/upgrade-to-percona-server-on-a-plesk-server-or-vps.2121/
We are already running it on P8ntballer. Huzzahs all around
Also included in this update is full Nginx web server support (You will need to add the remi repo before enabling this option). So not only can it be set up as a reverse proxy as is easily available in current plesk and cpanel versions, but it can now be set up with php-fpm to allow Nginx to serve all content on your site.
A full changelog can be found here: http://download1.parallels.com/Ples...lels-plesk-panel-11.5-for-linux-based-os.html