AT&T got rid of their unlimited data plans quite some time ago. However, folks who had unlimited data before the plan was removed are likely still enjoying the all-you-can-eat option.

Thanks to the grandfather clause, customers should get to keep those unlimited plans until they sign another contract — unless their iPhone happens to be jailbroken and they’re using an application like MyWi

9to5Mac reported this morning that AT&T is going to start forcibly switching jailbroken hotspot-ers off of their unlimited data plans beginning August 11th. While this won’t affect customers who utilize native tethering, folks who use apps like MyWi might want to pay attention.

An AT&T spokesperson confirms:

“Earlier this year, we began sending letters, emails, and text messages to a small number of smartphone customers who use their devices for teetering but aren’t on our required tethering plan. Our goal here is fairness for all of our customers (this impacts only a small percentage of our smartphone customer base).”

Yeah, we remember when AT&T started sending out the text messages of death to MyWi users back in March. And even back then they were threatening to force folks using the illegal tethering app into a tiered data plan.

While the August 11th date hasn’t been made official yet, BGR was able to confirm with the carrier that the move would be happening soon. It sounds like the enforcement date is different for each customer, based on when they received the original notifications.

At any rate, If I were a heavy MyWi user on an unlimited plan, I’d probably start looking for an alternative method — and soon. In a world where unlimited data plans are becoming a rarity, I wouldn’t want to risk losing mine so frivolously. Whether it’s fair or not is a whole different story.

Thoughts? Are you still using MyWi on an unlimited plan?