Blue - you're correct, there was a hack of some kind. From looking at it it seems to be mostly centered around Wordpress and getting those links onto the front page.
I'm going to do some maintenance very soon - probably within the next week or two - to move the ZP site to a fresh server, re-install wordpress and all software from scratch with latest versions, switch from Apache to nginx+PHP-fastcgi (if you want to get technical...), and relaunch it. Hopefully this will both clear out any effects and also harden the installs and prevent future problems, as well as speeding up the site significantly.
I'll post warnings and news before that happens in case there is any downtime, but in all likelihood it will be minimal as I'll just run the two servers simultaneously.