A Chinese company has recently been developing a case(skin) for the iPod Touch to have features like GPRS, Phone, Messaging, etc. Here is a Youtube video of the product.
http://www.youtube.com/watch?v=TR4T34grmYA
The product is expected to cost at around 300~500 rmb (which is around 45 ~75 US dollars), featuring an external battery cell, microphone,speaker, sim card slot, etc.

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