part of their summer sale. I think its available for a couple of days.
GOG normally have some good deals, worth checking out, particularly if you are in to older games. They also do things in Aus dollars :)
just a heads up, some good sales on GoG at the moment. Might be a portent of imminent Steam sales too? (i have no idea).
I am liking GoG, it appears to be offering some alternative to Steam, although nowhere near the scope of Steam currently.