Source: http://www.officialnintendomagazine.co.uk/29050/news/new-mario-sonic-london-2012-olympics-screenshots/
Here is the front Box art for the Wii:
The 3DS box art was not shown, but according to the source it also has a gold box art.
So we have white, black, red and now a yellowy-goldy colour Wii boxes. I wonder if there will be a new colour. More importantly I'm hoping Zelda SS will come in a gold box art.