In my opinion that would kill the whole point of the art book. You could probably get most of the information that's included within the artbook on the internet already, a PDF version would be pointless.
Having all the art and information in a pretty book is what makes it special...
I didn't realise I was being missed. It's been a very very busy couple of years. And I'm ashamed to say this, but I started to forget about Oddworld :O so I came back to rekindle the spark I once had.