As of this past Sunday (March 8) Marriott changed the points requirements for free nights at 20% of its Worldwide hotels. 300 of the hotels (roughly 9%) will increase by being moved up to a higher category level while 350 (11%) will decrease by being moved down to lower categories. Approximately 95% of the 650 hotels affected fall into the first 5 redemption categories.
Visit this thread on FlyerTalk.com to see a compiled list of the individual hotel changes
Source: Hotel Check-In