It actually allows for a discount on no-contract phones and only excludes a particular brand of tablet, and all Apple products. However, the coupon expires prior to the actual sale of the Xoom, so no discount on the Xoom. With the pre-order, you're only placing a down payment to guarantee you can purchase it a few days later, you aren't actually buying the device until launch day, 3 days after the coupon expires.
I wouldn't be surprised if another 10% off coupon comes out in the future. If it has the same wording as this one, it would probably be accepted, but I'll bet they will exclude Xoom in the fine print on future coupons.
HTC EVO 4G LTE - Stock
Samsung Galaxy Nexus - Stock
Motorola Xoom - Verizon - Rooted
HTC EVO 4G - Rooted
HTC Hero - Rooted
HTC T-Mobile G1 - Rooted