One of my favourite expressions is win-win, and the expression was recently used by Bryan Frith in The Australian to describe the Commonwealth Government's recent announcement relating to Telstra. The piece was headed "Reform package a win-win for all but Telstra." But given that Telstra is the major party in the reform package, surely this is a win-lose situation? How can youo have win-win when the major party loses?
The term applies in both game theory and conflict resolution, according to the Wikipedia, and according to the Wictionary, win-win is an adjective. And according to the Wikipedia article, non-zero-sum is a synonym. Brad Spangler, on the Beyond Intractability website, points out that a win-win situation doesn't necessarily involve everyone winning - but everyone believes he has won.
Nevertheless, I think that Telstra lost, making it a win-lose, or possibly a win-loss, to turn the expression into a noun.