When I first heard that the 8800GT was being released for the MacPro, I was mildly disappointed that it wasn't the GTX Ultra, but still *quite* glad for the upgrade. However, when I realized that it was only for the new macpros, I was quite annoyed.
I agree that it's high time for the x1900 to be updated. While so far its performance has been adequate (barely) for my needs (FCS2, Aperture, Maya, AND a whole lot of gaming via bootcamp), I am quite disappointed that the 8800GT is so far unavailable. When I first got my MacPro (about 6 months ago), I was willing to put up with what many others had described as an unsatisfactory card until a new one was released. Even though I haven't actually had any serious problems with it though, I am still frustrated with how events have turned out, as the x1900 is by now out of date compared to newer cards like the 8800GT.
At least Apple is working on it..