As you may know there is only a white version of the Mac mini. Today 123Macmini.com has shown some more colorful paintjobs from ColorWare for the mini:

“Mac mini owners who already have their Mac mini can send in their case to be painted for $99 dollars.” – So its not a new case – they just take the existing case and paint it.

Quelle 1: http://www.123macmini.com/news/story/24.html
Quelle 2: http://www.colorwarepc.com/