Found this via Yahoo:
How long can you store champagne? How should it be stored?
A search on "storing champagne" led us straight to some good advice. When it comes to wine in general, and sparkling wine in particular, temperature matters. All wines keep best in a cool, dark place with consistent temperatures around 55°F. Fluctuations of hot and cold can ruin a nice bottle of bubbly, and chilly extremes are just as harmful as high temperatures.
Don't keep a bottle of champagne chilled in the refrigerator indefinitely, waiting for a reason to celebrate -- by the time you pop the cork, it may not taste very festive. An article on storing wine from About.com recommends refrigerating champagne for no more than a couple of days. Return it to the somewhat warmer conditions of your wine cellar for longer term storage. If, like us, you don't have a wine cellar, the FAQ at Wine.com suggests that 45°F is the optimal temperature for both serving and storage.
The proper treatment of food and wine is part science, part opinion. In the past, we've found the information from Epicurious both helpful and accurate, so we were delighted to find their entry on storing and chilling champagne. Most champagnes store well for 3-4 years, but may deteriorate if kept longer. Vintage champagnes (those dated by year on the label) may keep for somewhat longer, but storing even the finest vintage champagne for over 10 years is not recommended.
Once a bottle of champagne is open, you'll need a special stopper to recork the opened bottle. A regular stopper could easily fly off in the refrigerator. Here's an unproven tip you might want to try: Set a silver spoon, stem side down, into an open bottle of champagne. This should keep the sparkle alive for a day or two in your refrigerator.
And just in case you were wondering: All champagne is sparkling, but not all bubbly wine is technically champagne. Only wine made in France's northern Champagne region according to the age-old Méthode Champenoise may be labelled champagne. Everything else, no matter how delicious, small-bubbled, or expensive, is simply sparkling.