When do the Radeon 8000 and Nvidia 700 series come out?

The Radeon HD 8000s will probably launch sometime this winter. I haven't heard any rumors about the Geforce 700 series (apart from when the 600 series was mistakenly referred to as such), and my guess is it will arrive later.

Since the GTX 6xx series has recently rolled out, the 7xx series will likely be released next year.

AMD is pretty quick maybe end of this year, it all depends on what AMD does. If 8000 series makes its debut this year then Nvidia could paper launch but thats about it. 700 series will be launch probably second quarter 2013

March 2013 for the GTX 780.
http://www.guru3d.com/news/no-nvidia-geforce-gtx-780-be...

problem right now for both amd and nvidia is geting the smaller fabs out of of the foundry. right now the foundry on a learing curve and yealds are lower then both amd and nvidia would like.