L' Eomot Inversé (8/11/2012)
But one niggle - either the explanation is wrong about NONCLUSTERED being a mandatory keyword for CREATE COLUMNSTORE INDEX, of BoL (the page you reference in the explanation) is wrong about it being an optional keyword - it's shown in option brackets in the BNF description of the statement syntax, so that it appears that although the index must be nonclustered it isn't neccessary to supply the keyword. I don't have SQL 2012 handy so can't check whether this is a BoL error or not.
You are absolutely right, Tom. I made a mistake there. Luckily, the mistake doesn't affect the correctness of the answer. The keyword NONCLUSTERED is optional, but if you leave it out you still get a nonclustered columnstore index - and if you change it to clustered, you get an error message stating that clustered columnstore indexes are not supported.