UPDATE: The for-real white PS Vita is finally being released in Japan, check here for details. And in the west, it will come bundled with the Vita's Assassin's Creed III game at the end of October 2012.
Anyway, someone took a decent pic of it and posted it on Twitter, and it looks pretty neat. Personally I prefer black for my gadgets, but white just adds a slight futuristic touch. However, with the trend for those PS Vita screen protector skins/desktop backgrounds, the basic colour could soon be an afterthought.