Nope, it's not a joke.
H2G2 is the Hitch Hiker's Guide to the Galaxy (the DNA in the address are the initials of Douglas Adams). H2G2 is basically a collection of articles that people contribute to compile the said book.
There are several versions of H2G2 dotted around the web, although this one is the 'official' version. Looking around you can find them for every platform (I've got a good one for the Psion 5 somewhere...)
I look forward to having the time to work through the proof :)
Take care (and dare I say, Don't Panic...)
Maths Geek and proud of it!