This iPhone 4 money clip is either the best or the stupidest solution to the wallet/iPhone carrying problem that I have ever seen. The trouble is, I can’t quite work out which it is.
On the one hand, a permanently attached clip is good for all sorts of things, not just money. You can secure the iPhone into a shirt pocket to stop it tumbling to its doom every time you lean forward, clip the iPhone to a notebook (the paper kind) or use it to carry a credit card (or three — the maximum number that will fit.)
But on the other hand, you now have an easy-to-snag hook attached by screws to your delicate pocket computer. You also have a big metal clip ready to bash in the iPhone’s brittle rear glass panel.
What is neat, though, is the little screwdriver that comes with the stainless steel clip. It is double ended, with a head to fit the iPhone’s weird screws and the clips Philips-head screws.

So, if you have $32, don’t care to use docks or cases, or that even your charging cable won’t sit properly in its socket, then go ahead. Just remember this warning from the product page:
We cannnot [sic] be responsible for any damages this product may cause to yourself or your iPhone 4.