updated 02:45 pm EDT, Thu August 4, 2011
Can disable unlimited plans
AT&T is starting to force capped iPhone tethering plans on people with unlimited data plans who have been tethering their devices via jailbreak, accounts suggest. The carrier has held a forced switch policy for some time, but is now allegedly giving people fixed deadlines, possibly with a hard cutoff of August 11th. Under AT&T's official data plans, tethering requires paying $45 a month, and limits total data usage to 4GB before overage rates apply.
An AT&T spokesperson is not confirming the deadline, but is saying that customers have only three options. The first is to stop tethering entirely, which also allows people to keep any previous data plans including the unlimited option. Alternately people can opt into a tethering plan voluntarily, or wait for the forced switch "after the date noted in their customer notification."