Apple sent the following email to customers who had purchased the Mac Pro with the ATI X1900 Video Card Build-to-Order option.
Apple is pleased to announce a price drop for the Mac Pro you recently
ordered. We have automatically adjusted your order to reflect the new price.
For up-to-date information on your order, please visit our Order Status
website at http://www.apple.com/orderstatus. Once your order is shipped, you
can also obtain tracking information on this site.
Thank you for your interest in Apple products.
The Apple Store shows that the ATI X1900 dropped from $350 to $250 for build to order purchasers of the new Mac Pro. Meanwhile, the individually sold card also represents the lower price at $399 (vs $499).
The ATI X1900 was announced alongside the Mac Pro but has yet to start shipping.