According to a forum poster on the rock band forums. EA has sent an email saying that if you ordered a Rock Band replacement guitar and it hasn't come yet you will be getting a free EA game. Here is the email.
Congratulations on your purchase of Rock Band!
After reviewing our records, we see that your recent request for a replacement guitar has been subject to an unacceptably long delay due to a late shipment from our manufacturer.
By the time you receive this, your replacement guitar should be on its way to you. However, the Rock Band team is committed to providing a world-class customer experience and we do not believe we have met this commitment in connection with your request. As a token of our appreciation for your patience and understanding, we will be offering you a FREE EA game. Details will follow shortly.
We are sorry if your first experience with Rock Band has not met your expectations. We hope our gift will show you how committed we are to your satisfaction.
The Rock Band Team"