Release Date For AMD HD 5800 Series: September 22nd
 

The Radeon HD 5870 1GB should sell for $399 at launch, while Radeon HD 5870 2GB should sell for $449. At the same time, the slower Radeon HD 5850 with 1GB memory will sell for $299. The launch date for all three cards is September 23rd in Europe whereas in the US we are talking about the 22nd.

http://www.fudzilla.com/content/view/15434/34/