The incentives of the Xbox Live Rewards program come in the form of Microsoft Points, the currency used in the Xbox Live Marketplace, with the exact rewards depending on which level of the promotion users are enrolled in.
Three levels have been uncovered thus far: Gray, Orange, and Green. Gray participants will be refunded a small percentage of their total Marketplace purchases, with the percentage growing the longer they stay subscribed to Xbox Live Gold.
Orange offers the above along with additional Microsoft Points for renewing an Xbox Live Gold subscription, subscribing to Netflix and making one's first Xbox Live Marketplace purchase. Green, meanwhile, offers the same incentives as Orange minus for the percentage-based Marketplace refund. All three levels reward participants with 100 Microsoft Points ($1.25) for providing feedback through a program survey.
The invite-only promotion will run for the next six months, with the results of the program likely influencing whether or not it will later be made available to all of Xbox Live. Those in the program won't be able to spend the Points they earned until the third month.