I think this is a stunning idea.
The more devs that get together the better, plus some of the pre-order "consumers" too as feedback for devs always helps.
If this could be made more official by getting somebody from Ouya themselves visit it would be great. I can only see this being a positive thing for Ouya Publicity and helping keep momentum after the end of the kickstarter. The more this is in the public mind the better the launch will be and more likely it is to hit retail as a success.
Maybe somebody should get some official Ouya merchandise, keyrings, usb sticks, stickers or T-shirts etc for the event.
I can only see this working well with Official Ouya support, but whatever happens, A developer get together would be wonderful.