Sony revealed that those that make a PS4 pre-order after the 6th of August might not get the console at launch, this due to high-demand. This comes after Ubisoft had previously said that pre-orders for next-gen consoles doubled the previous generation.
ShopTo is displaying the following message: "Sony have confirmed all PlayStation 4 pre-orders placed from 6th August will now not be guaranteed for launch. You can still pre-order PS4 with us in case we receive cancellations and can fulfil your order for launch."
A similar message can be seen in Amazon, but for the moment, this only applies to European retailers. This had already happened before at GameSpot when it announced it was putting the PS4 pre-orders on hold in July, with retailers saying that pre-order interest was at peak levels.
It's uncertain if this will be applied to the US and Japan anytime soon, but with the PS4 being the favourite of the next-gen consoles and with a somewhat inviting price, it wouldn't be surprising if PS4 supplies wouldn't be enough for the demand. The PS4 will be available before the holiday season worldwide.