http://www.forbes.com/feeds/ap/2011/07/31/general-eu-portugal-cork-apos-s-comeback_8593469.html
I also found an interesting study on screwcaps, which makes some of them look pretty good, if it's to be believed:
http://twistopenhogue.com/home-page/
The take away:
- Screwcaps can be as good or better than natural cork
- Not all screwcaps are created equal