A report by Andriasang claims that Sega has chosen tomorrow, June 23 to launch the demo for its remastered retro remix, Sonic Generations. Although it doesn't cite a source for the information, the site says that the demo will be available for PS3 and Xbox 360, the latter requiring an Xbox Live Gold account to download. Additionally, the one-level trial game will evidently expire on July 12, vanishing from both e-stores and disabling itself if it's been downloaded.

Sony Computer Entertainment Europe has listed the demo as part of tomorrow's European PlayStation Store update, lending a lot of credence to this news, although a representative for Sega America couldn't comment when asked by Joystiq if the demo is planned to hit the US tomorrow, too. It's entirely likely -- though not confirmed -- that the demo's release is being prepared as a surprise to celebrate the 20th anniversary of the Sonic franchise, which is, conveniently, June 23.

PS3 owners in Japan would need another surprise tomorrow in order to play the demo, Andriasang points out -- that country's PSN is still offline, with no indication it will be brought back into service within the next 24 hours.

Update: The Sonic Generations demo is now available on Xbox Live -- for the next 20 days.