According to SprintFeed, the last carrier to allow unlimited data will move to cap tethering plans to 5GB starting October 2nd. This move likely comes in preparation for the onslaught of iPhone users, who are expected to chew through lots and lots of bytes. Sprint will continue to offer unlimited data for mobile data (but for how long?), so if you tether through shady means you may be able to skate by unnoticed. Tethering costs $30 per month and includes 3G/4G access, and overages are $.05/MB. Existing users will not be grandfathered in and will be automatically migrated to the new plan.