The TwelveSouth BookBook range of cases have proven themselves to be some of the most popular iOS and OS X accessories available on the market. Uniquely imagined and beautifully styled, the BookBook case is basically a rather gorgeous looking wallet and iPhone case combo that is manufactured to look like a vintage book on the outside. The quality of the product speaks for itself but with current versions only being compatible with the iPhone 4 and 4S, TwelveSouth have found themselves issuing a statement about the imminent availability of a BookBook case made specifically for the iPhone 5.

There is no doubt that manufacturing cases for a device which hasn’t even been announced – let alone seen – is risky business. The case makers have been hard at work, relying on tips from the proverbial “sources familiar with” the design phase of Apple’s upcoming smartphone, in order to gain an advantage over competitors and draw first blood from the lucrative market.

If you’re a regular reader of this site, then you’re likely aware that the next iPhone is scheduled to be announced later this month. Want proof? In certain wholesale markets in China, as well as Chinese e-commerce sites, iPhone 5 cases are abundantly available, with characteristics that point to changes in the device’s form factor.

It wasn’t long ago that we reported of the iPhone 5 silicone cases which had begun selling on the internet – sourced mainly from China. It seems that wholesaler TruSupplier is very confident on the outcome of the final design, and has subsequently added hard-shell cases to the roster in anticipation of the launch, expected to be early October.