According to the guys over at iPhone Atlas, accessory maker USB Fever is planning to offer a hardware-based unlocking device for Apple's iPhone 3G handset on August 20th.

The company is taking pre-orders for a US$35 SIM unlock that consists of a micro-controller mounted to a 0.10mm thin piece of FPC that fits between an operator's SIM card and the phone’s SIM socket. The device will allow the use of an unauthorized carrier SIM card in the iPhone 3G.

The product description for the unit reads as follows:

Because of it’s very thin and slim design it fits into almost all phone’s on the market and can also be easily removed again. It’s got Gold Immersion and makes perfect contact with the card and the socket at all times. Cutting of your Operator’s SIM card is required but kept to a minimum.

This SIM unlock is a revolutionary do-it-yourself Plug & Play card for unlocking iPhone 3G without the risk of damaging the iPhone 3G or voiding it’s warranty. This SIM unlock is inserted into the iPhone 3G in parallel with your operator’s SIM card and enables you to use your card on phones locked to another provider.

Stay tuned for more news about this and let us know what you make of it over in the comments or forums.