Looks like Apple is tightening its iron grip over the iTunes App Store. The big fruity company has been reported to have rejected Sony’s eBook store app – the Sony Reader Store from the iTunes App Store. The reason for the rejection was due to changes in Apple’s App Store policy – all in-app purchases will now have to go through Apple. It looks like apps that sell their own content will not be allowed on the App Store in the future. The new policy suggests that Apple might be planning to set foot in the eBook business, competing against Barnes & Noble, Amazon and the like. What about games with in-app purchases or existing eBook readers like Kindle? With Apple’s The Daily announcement coming up tomorrow, let’s see if they shed any more light on the subject. Stay tuned as we find out the fate of existing apps that have already been approved for the iTunes App Store.