From this thread,
The Wii U was at 3.6 million and is now at 4.5 million. Ouya had claimed from twitter whether by accident or other wise they would be at 5 million by the holiday season before the European shipments. Now the Wii U has done bit well this holiday, and I am not sure how close to 5 million OUYA was. but i doubt it sold more than say, 900k during the holiday. since the Wii U is still (barely) in the lead do you think Ouya is the current leader now?