it hasn't been stated one way or the other. If apps can be side loaded, then I would say even if it's there, you could extract Google Play and loaded it that way, as well as the apps you want. The only thing that isn't know, what apps will play nice with Ouya's interface using a controller. A lot of apps, if not all, are designed from a touch input design.
I don't know if there is anything that Google Play needs besides an Android OS to function. So there could be reasons it may not work despite being able to load it on the Ouya.