You might have heard of the Apple Peel or maybe the ZTE Peel offered by Sprint.
In November, Jim Karpen reported in his post here about the ZTE Peel accessory which allows Ipods to access Sprint’s 3G network for data transfers. However, if you want to make voice calls, you'll need to use Skype.
There is a similar Ipod accessory called the Apple Peel that was invented by a pair of Chinese brothers that takes this one step further. Basically, it is an Ipod case with a simcard slot that allows the Ipod to makes calls and text messages. It requires the installation of an app for phone calls and a text-messaging app, onto a Jailbroken Ipod. (Note: Jailbreaking voids all Apple warranties!) If you read mandarin, their website is over here.
(screenshot taken from www.peel520.net)
The 1stgen Apple Peel does not support data transfer over GPRS. Neither did it support the latest Ipod Touch 4G. However, according to their website, this capability as well as the latest gen Ipod Touch will be supported by their 2ndgen Peel that is due for a launch date of 20thJanuary 2011.
There are various online stores such as this one that claims to offer shipping of Apple Peels worldwide with a retail price of US$89. I haven’t tried any of them but these site are at least useful for being able to explain in English (with pictures) how the Apple Peel works. If you happen to be in Shanghai and Hong Kong, I am told that it is easily available at any of the major electronics bazaars.