Fly Me To The Moon, thank you for starting this. Sorry, all, for the vertical space this will take. I emailed GPCS when this was announced, and suggested they find a simple way to list the properties up front that do. For their sake more than mine. It's a very good enhancement, but they've put their light under their hat. It's difficult for customers to exploit it "flying blind". Their reply, on 29 May 2006, was that the folllowing properties participate (given in a pretty convenient order, IMO):

Hyatt Regency Aruba
Grand Hyatt Atlanta
Hyatt Regency Atlanta
Hyatt Regency Lost Pines Resort & Spa
Hyatt Regency Bethesda
Hyatt Regency Cambridge
Hyatt Regency Baltimore
Hyatt Regency Calgary
Hyatt Grand Champions Resort
Hyatt Regency Chesapeake Bay Golf Resort
The Hyatt Lodge (Oak Brook, IL)
Hyatt Regency Chicago
Hyatt Regency O'Hare
Hyatt Regency Woodfield
Hyatt Regency Cincinnati
Hyatt Regency Santa Clara
Hyatt Regency Cleveland
Hyatt Regency Columbus
Hyatt Deerfield
Hyatt Regency Denver at Colorado Convention Center
Hyatt Regency Tech Center--Denver
Hyatt Regency DFW
Grand Hyatt DFW
Hyatt Regency Dallas
Hyatt Dulles
Hyatt Fair Lakes
Hyatt Regency Greenwich
Hyatt Regency Waikiki Resort & Spa
Hyatt Regency Houston
Hyatt Regency Huntington Beach
Hyatt Regency Indianapolis
Hyatt Regency Jacksonville
Hyatt Regency Lake Las Vegas
Hyatt Regency Long Beach
Hyatt Regency Miami
Hyatt Regency Crown Center (Kansas City, MO)
Hyatt Morristown
Hyatt Regency Minneapolis
Hyatt Regency New Orleans
Hyatt Regency Coconut Point Resort & Spa
Hyatt Regency Jersey City
Grand Hyatt New York
Hyatt Regency Orlando Airport
Hyatt Regency Pittsburgh International Airport
Hyatt Regency Newport
Hyatt Rosemont
Hyatt Regency Sacramento
Hyatt Regency Islandia
Manchester Grand Hyatt
Hyatt Regency San Antonio
Hyatt Regency Savannah
Hyatt Regency Scottsdale
Hyatt at Fisherman's Wharf
Grand Hyatt San Francisco
Hyatt Sarasota
Hyatt Regency St. Louis
Hyatt Regency Tampa
Grand Hyatt Tampa Bay
Hyatt Regency Lake Tahoe
Grand Hyatt Washington
Hyatt Regency Crystal City
Hyatt Regency Washington
Hyatt Regency Wichita
Hyatt Regency Vancouver