A retailer lists the PS4 to be releasing on November 13th 2013, even though Sony has not given a date at all.
Below is a picture found on NeoGAF for the PS4 release date in an Amsterdam branch of games specialist Media Markt. The picture seems legitimate, but could very well be a photoshoped version to the original.
Sony has not revealed anything officially, except that they promise the system will be availible world while before Christmas of this year. retailing at $399 US, €399 in Europe and £349 in the UK.
We will just have to wait to see what Sony says.