From the website:
Pledge to switch off your lights for one full hour on Saturday, March 26, 2011, from 8:30 to 9:30 p.m. local time, and receive 100 bonus Starpoints®. Join the more than 500 Starwood hotels and resorts around the world that will be observing Earth Hour this year. It’s a small commitment to the environment we all can keep. Together, we can make a bold statement against climate change.
Don’t forget, the Starwood Preferred Guest® Credit Card from American Express gives you 10,000 Starpoints after your first purchase and an additional 15,000 Starpoints when you spend $15,000 in 6 months-enough for two free nights at the Westin St. Francis in San Francisco, the W Boston or any other category 5 hotel.
Discuss this free 100 Starwood points in our Forums!