R600 based Radeon HD 2900PRO and 2900GT cards are going to be very limited . ATI and all of its partners decided not to ship the review samples simply because this product has roughly two months to live until the replacement part arrives.

RV670 is just around the corner, it should be ready for a November launch and this chip is definitely a better choice for a mainstream card as it will be smaller and cooler.

The HD 2900PRO sounds like a great card for not so much money, but it doesn't look like it will be readily available in many places.