Virgin Mobile introduced the ZTE PEEL 3200: http://www.virginmobileusa.com/mobile-broadband/peel-3200.html?
, a casing for iPod Touch 2nd and 3rd generation models (1st and 4th models
are out of luck for now). The case costs $100 and has a no contract 500MB
plan (Appx. 25hrs of 3G access) for $20/Month on the Virgin Mobile network.
In order to turn your iPod Touch into an actual phone, download the
Talkatone: http://itunes.apple.com/app/id397648381
Application from the Appstore and set up a free Google Voice: http://www.google.com/chat/voice/
Account from your computer. You will be able to make free phone calls to
the US and Canada via your iPod Touch where ever you have WiFi or 3G access.
This a good way to cheat paying $40 a month for contracted phones and
eliminates the need to bring both your iPod and phone with you wherever you
go. All and all, it's like having an iPhone on a $20/Month plan.