I've heard that all wines will gradually go over to screw caps, which are better than synthetic corks. Real cork is getting in to short supply.
Just found a bit pn the inet:
One thing that is starting to change is the wine industry's attitude towards cork stopper vs. screw cap. For the first time in history more people in a recent Gallop poll said that they preferred wine to beer as their drink of choice. As a result of the increased production by wineries, there is a greater chance that we could come down with a bottle of "corked" wine. The term "corked" means that mold has affected the cork, leaving the wine with a musty taste and smell. This can affect almost one in every twenty bottles of wine. Some of the major wine labels have responded by using synthetic corks, which really don't make sense because they are difficult to remove and almost impossible to reseal.
The screw cap, or Stelvin cap, is a more logical choice. They form a better seal and are very easy to screw back on. Consumer reaction to the screw caps has been good and growing all the time. Nothing is worse than showing off a very expensive bottle of wine, and then realizing after you open it that it's gone bad. A recent survey showed that about 60 percent of all American homes don't even have a corkscrew. Some of the wineries have been slow to change and the cork companies are working on making the natural cork more reliable using more sophisticated testing. Until then, it's down to a battle between the screw-cappers and the traditionalists, and it's up to the consumer to decide.