Xbox Live Gold subscribers with a Gamerscore of more than 3,000 points will now receive rewards during their birthday month.
Players with a Gamerscore of between 3,000 and 10,000 will receive a “special gift” during their birthday month. Over 10,000 will receive the gift and a 1 percent rebate on Marketplace purchases every month. And over 25,000 will receive the gift as well as a 2 percent rebate on Marketplace purchases every month, according to Kotaku.
This is all part of the MyAchievement program that new to Xbox Live, with more details available here.