The "bridge" in this case happens to be a bridge chip. DigiTimes is the intrepid tech site bringing us the wonderous news today. The new A05 bridge chip will allow the 8400 and 8600 series (No 8500 series?) to work with your tried and true AGP motherboard. Apparently the A05 will be able to work its dark voodoo magic with the soon to be released G92 and G98 as well.
Now check out my crappy joke pic made with MS Paint! (If you can do better, please leave the URL for your pic in the comments.)