Tree scientist Nalini Nadkarni in her excellent new book Between Earth and Sky explains cork trees and the cork industry, and in a quiet scientific way mentions why you should want the real stuff in your wine bottle.
She writes that the cork industry has evolved over hundreds of years, and supports a substantial industry of cork orchardists. The trees are in no way harmed: in fact, it takes forty years before a tree can produce cork suitable for wine bottles, and trees usually live for centuries. The cork also supports:
Speaking of renewable, here's a photo from Ernst Schade of a cork forest in Portugal via the inexhaustible flickr. Echoing Nadkarni's explanation, the photographer mentions that the number on the bark of the tree means that it was harvested in 07, and so won't be harvested again until 2017.
Kit Stolz 