Dual SIM card adapter for iPhone 3G/3GS?

USB Fever has an interesting product in their matrix this morning.  The Q-Dual SIM card adapter apparently allows you to manually switch between two SIM cards in your iPhone.  The package also includes an external battery and case in one package.

It isn't clear whether this bypasses Apple's carrier exclusivity settings or, for instance, you would just need two legit AT&T SIMs.  It seems to be geared toward international travellers who might have an AT&T card in the US and a O2 SIM when travelling to the UK, for example.  They offer the instructiosn below:

Installation:
See pictures above plus
- Home ==> settings ==> Phone ==> SIM Applications: select your desire SIM card
(If you don't want it to select SIM card for you when the signal is low, please don't select "auto/SW)

Note once you've chosen to another sim card, it will have a message "No SIM Card installed", please wait 1 or 2 minutes, it needs aound 1 ~ 2 minutes to search, during this time, "No SIM" will appear in the top right of your iphone's screen.
- When the battery is with the case, the LED will be always on (blue). When the battery is being charging, it will be in Red.
- For sync with PC / charge with PC / Mac, please turn the Charge Button to "OFF" - This devices does NOT support DUAL STANDBY Mode but you can switch between them.
- Due to complexiety of network compatibility, we cannot 100% guarantee its compatibility with your network, we can only guarantee the compatiblity of the battery part, but if you have probelms of compatibility, we will try our best to help you.