As Engadget points out, Vooma's new Peel PG92 isn't the first dual-SIM case for the iPhone, but it's probably the nicest-looking one. The planned case consists of a battery pack to charge your phone and an unlocked SIM slot that adds dual-SIM capability, but it requires a jailbroken iPhone 4 or 4S and a companion app.
TechCrunch tested a pre-release model, calling the Peel PG92 a "dumbed-down cellphone." Once the app is installed on jailbroken phones, a user can control the phone inside the case. The site said other than few sacrifices in rendering the interface that interacts with the second SIM card, it found that using Peel PG92 to place calls using the second SIM card worked seamlessly.
There's no price or availablity information yet, but those interested can sign up for more information through Vooma's site.