SPG tweaked some terms and conditions of the program last time on January 17, 2013, and just made some updates earlier today. You can access the current terms and conditions here.
SPG members have been eligible for night & stay credits for up to three rooms at a time since October 2011, but this has never been on the actual terms and conditions previously
Food and beverage spend
The banquets, meetings & functions food and beverage spend is excluded from the Starpoints. (There is separate program for that)
Converting Starpoints to miles
You cannot cancel or reverse a Starpoint conversion to miles.
SPG reserves the right to correct any promotional postings at any time.
Toll free number
References to toll free numbers have been deleted.
SPG reserves the right to change anything at anytime.
SPG can now terminate the program in 12 months instead of the previous 9 months advance notice.
Not huge changes, but I would prefer getting an email from loyalty program, whenever they tweak their program terms and conditions.