Very good step by step tutorial he did there and a great effect you can achieve with it. If you don't know this one already have a look I can really recommend it.
And if you are there you can also just have a look at the other terrain tutorials or the loads of stuff he has on his blog.
So long,
Paradox0n
P.S.: Welcome aboard Zzzzzz. The next wave of Majorca impressons is work in progress and will be posted soon :)