Do you have multiple cell phones for personal and business purposes? A company called Vaveliero has figured out a way to help you cut back on your mobile devices. Vaveliero has invented an iPhone 4 case that allows you to use multiple SIM cards on one phone.
The accessory replaces the iPhone 4′s microSIM slot with an external SIM adapter giving you the option of using two accounts on one device.
It's unclear if you need an unlocked phone to use more than one carrier, and the different accounts can't be used at the same time. But it's a cool feature that could come in handy at the office by allowing you to carry one device to work, and by giving you the option to switch to your personal line at quitting time or during breaks.
The case may be more useful in other countries for switching to different carriers, but it's still an interesting accessory that could be utilized in the U.S.. Especially if the rumors about Apple adding Sprint and T-Mobile in the future are true.