Nintendo has won. We all know that. They are printing cash.
Microsoft has won. They increased marketshare dramatically and solidifed their spot in the market heading to next gen. They have made their way into people's living rooms and may even turn a profit, even if they do end up 3rd somehow.
Sony could be the big loser. Their development costs were so high, and if Blu-Ray doesn't become a dominant format before the direct-to-viewer download/streamed entertainment hits, they are the big losers. They have dropped considerably in marketshare, and have a LONG way to go before they break even. They could make a run at respectability yet, no doubt. But they are the only company of the big 3 that could be seen as losing this gen. PSP and PS2 is helping soften the blow, but if you look just at PS3 they are pretty sad as of now.
I personally hope they pull through fairly healthy, but I have my doubts. I think they are needed in the market.