I have not been... but here is the info from the DVC Member website:
Top of the World Lounge perk extended through Dec. 29!
The popularity of a special perk originally slated to end on Aug. 25 has prompted its extension! From now through Dec. 29, 2012, Disney Vacation Club® Members staying at any Disney-owned-and-operated hotel at the Walt Disney World® Resort (whether they booked with vacation points or cash) may enjoy complimentary access to one of the vacation kingdom's most exclusive spaces: the Top of the World Lounge atop Bay Lake Tower at Disney's Contemporary Resort.
Note that Members traveling from other resorts must use Walt Disney World Transportation, as parking will be unavailable to anyone not staying at Bay Lake Tower or Disney's Contemporary Resort. Upon arrival, Members must walk to the Bay Lake Tower main lobby entrance on the ground floor (the typically locked front door will be unlocked during this time, or a Cast Member will be at the door to assist) and check in at the Top of the World Lounge desk in the lobby.
The sleekly designed bar and lounge, typically available only to Members staying at Bay Lake Tower, operates from 5 p.m.-midnight daily and offers spectacular rooftop viewing of Wishes the Magic Kingdom® fireworks spectacular complete with the show's stirring musical soundtrack. The ability to access the lounge has been a frequent request from Members staying at other Walt Disney World Resorts since Bay Lake Tower opened in 2009, and Disney Vacation Club is thrilled to make that "wish" come true during this extended period.
This perk is available exclusively to Members and those in their traveling party who are staying on that Member's reservation. At least one Member in the traveling party must accompany the group and present his or her current Key to the World card displaying a Disney Vacation Club Membership notation in order to gain admission to the lounge. If the Member's Key to the World card doesn't display a Membership notation, a Disney Vacation Club Member ID is required in addition to the Key to the World card to verify Membership.
This special Top of the World Lounge access is available on a first-come, first-served basis until the lounge reaches capacity. As the lounge is particularly popular during the Magic Kingdom fireworks, arriving as early as possible will give Members the best chance of gaining admission.
