Sony have announced that some lucky people will be getting an email this weekend with a voucher code to download the God of War III demo that was shown at this years E3, Gamescom and Tokyo Game Show. The voucher code will only be sent out to those who have registered for the SCEE promotional newsletter, so if you haven't, unfortunately it's too late:
"For those of you who haven't had the chance to play the God of War III demo which was on the show floor at E3, Gamescom, Tokyo Game Show and other SCEE events throughout 2009... well... some GREAT news for you: we will be emailing out some demo voucher codes to a selected number of PAL PSN users who registered to receive the SCEE promotional newsletter. If you haven't opted-in to receive it, it's unfortunately too late to be in with a chance to be picked for this promotion, but it's worth you registering today to be considered for future SCEE offers (simply go to the PlayStation Network icon on the XMB, select Account Management => Account Information => => Notification Preferences, and tick the relevant boxes).
Make sure you check your email inbox over the weekend and hopefully you will be one of the lucky ones to receive a voucher code allowing you to download this demo instantly from PlayStation Store! Remember, it's a random selection and only a limited amount of vouchers are being sent out so good luck :)"