Googleplex: first use

I was reading a bit of Hitchhiker's Guide to the Galaxy this morning and noticed a familiar word. Googleplex. As in "the Googleplex Star Thinker in the Seventh Galaxy of Light and Ingenuity" from Chapter 25 of Hitchhiker's. I was really shocked and just a bit awed. But then I googled it and sure enough, on the wikipedia entry for googleplex there is a quote from Douglas Adams.