Reward = A key
Book published in 2003
Not solved as far as I know.
Author's website = www.thewhistlepig.net no longer exists. Never heard of anyone that accessed the site to get info on what was there.
Author seems to have taken a low profile.
The key may not uinlock anything and is probably nothing more than just a key. I am unsure. Author didn't expound on the value of the key.