BRIDAL GOWN PRESERVATION BellaOnline has some interesting tips:

Do not take your gown to a dry cleaning service. Dry cleaners would like you to believe that their service is best, but in fact, you can do a better job yourself for less than what they charge. When your gown is dry cleaned, damaging dry cleaning fluid becomes trapped in the garment fibers. After an extended period of time, especially when sealed in an airtight box, this fluid may seriously degrade the fabric.