The SAFE Wallet is available in an iPhone 5 model, as well as an iPhone 4/4s model and is built by BulletTrain.
The SAFE Wallet is capable of holding the thickness of 5 credit cards, or 15 standard size business cards. It also holds your iPhone in portrait or landscape orientation on any flat surface, as well as being able to hold and conceal all kinds of other valuable things, like cash, keys and coins.
At present, the team of SAFE Wallet is raiding fund at Kickstarter. Pledging $39 will let you own the iPhone 5 case with integrated wallet.
Here you have the Kickstarter video presentation: