Nvidia is very excited about this news, AMD...not so much. I checked AMD's news page and they haven't even mentioned it yet. Nvidia says they are doing it because their customers have asking for it but I am not sure that is 100% true. Nvidia cares about what makes them money and about preventing bad press.
I think Nvidia is doing this because they are facing more competition from Intel on the integrated graphics processor (IGP) front and they believe that AMD's new Bulldozer processor line will be an attractive option to PC gamers. I want to know how AMD feels about this. Do they have any say about the features that MSI, or Gigabyte can include on their AMD based motherboards? I think they have at least a little influence don't you? One things for sure though. This is a good deal in the eyes of PC gamers everywhere.
This a picture of Asus' Crosshair V Forumla motherboard from their Repuplic of Gamers line. The picture is not huge, but the SLI logo is there on the bottom.