If you log into dvcmember.com, find "Member Perks", "Recreation", "Water Activities", you'll find the rules but the blackout dates are for 2007.

The latest DisneyFILES magazine lists the 2008 blackout dates on page 28, but not the rules..
So, here are both, in one place for you :
From dvcmember.com
"You and any Guests staying with you at Disney's Old Key West Resort, Disney's BoardWalk Villas, The Villas at Disney's Wilderness Lodge,
Disney's Beach Club Villas or Disney's Saratoga Springs Resort & Spa
are permitted to use other Disney Vacation Club and Walt Disney World Resort hotel pools (in addition to the pool at the Resort hotel at which you're staying) if they are not at capacity.
Pool hopping is not available at Uzima Pool at Disney's Animal Kingdom Lodge and Stormalong Bay at Disney's Yacht & Beach Club Resorts or at the leisure pools of these two Resort hotels. There are no exceptions to this policy.