In a live conference with the press today, CD Projekt RED—developers of The Witcher series—announced that they were currently developing The Witcher 3. This is according to websites Beefjack, Gamepur, and The Sixth Axis, who supposedly participated in the event.
According to the report, the game is slated for release on both the Xbox 360 and PC, where it is also being developed for the PlayStation 3 for the first time in the series. The game's executive director John Mamais could not confirm a release date for the game, but we speculate that the studio is targeting a 2013 release window, especially since the second game in the series—The Witcher 2—has been confirmed for release on the Xbox 360 this year.
When asked if they had any plans to bring The Witcher 2 to the PlayStation 3, they couldn't provide a simple yes or no answer, but said that "it would be stupid not to." I think we can safely assume that a version is currently in the works—assuming the reports are true.
We'll be confirming the information with CD Projekt RED shortly.
Update: CDP denies the report here.