If you really are interested in the textures, mapping, ect. (the game engine) Give Anet a bell, email them and ask nicely about it and if they're feeling generous, you may get some insight.
I doubt they'd actually give it to you though. Go and drop in a resume and if you're qualified enough, you could start working on GW itself :>
To the dude who wanted to know about the GW.dat unpacking
Sekkira