I think it is only at DVC Resorts but the listing on the member site is not specific:
>>Admission Discounts
DVC Members receive a 10% discount on the Walt Disney World® Resort Ultimate Park Hopper admission (valid from check-in through check-out dates). You also receive a discount of $4 per person ages 10 and up and $3 per person ages 3-9 on daily admission to Disney's Blizzard Beach Water Park and Disney's Typhoon Lagoon Water Park, and a discount of $4 per person at Downtown Disney® Pleasure Island.<<