The US Postal Service recently released their new stamp issue schedule for 2005, and I see that there's an issue on "Masterworks of Modern American Architecture" listed for May 12.
You can see a picture here (scroll down to the specific issue, click on the picture to enlarge it):
Interestingly, the stamp designers chose monochrome photographs. But many of them are of architectural details and, on first glance, don't strike me either as good photographs or as effective representations of what's special about the buildings, even taking into account that designing for thumbnail size makes different demands from composing for a 16x20.
The initial press release doesn't say who the photographers are. Does anybody recognize the work shown? Or perhaps it was newly-commissioned for this purpose...