FreedomPop has announced the Freedom Sleeve Rocket ($99), a case that turns the fourth-generation iPod touch into a device that can use 4G wireless data, in addition to acting as a Wi-Fi hotspot for up to eight devices. The Freedom Sleeve Rocket allows for a minimum of 500 MB of free wireless data per month — the device uses Clearwire’s 4G network and is scheduled to expand on Sprint’s 4G LTE network next year. While using data on FreedomPop’s…