When Apple unveiled the original iPad all the way back in 2010, it was only available on one network – AT&T – and the 3G-capable version only had two data plan options: $14.99 for 250MB of data, or $29.99 for unlimited. For some users 250MB of data was enough. Others, however, wondered why they should pay $15 for 250MB of data when for only $30 they could have all of it. Those users chose the unlimited plan.

Within a month of the iPad’s launch, AT&T had dropped the unlimited data plan as an option. Those who had it were allowed to keep it, but new users had to choose from one of AT&T’s new tiered plans. Unlimited data was no more.

Fast forward two years to the launch of the new iPad. Since nixing the unlimited plan, AT&T has allowed customers who signed up for it to keep it through all their upgrades (in fact, I’m still sporting the unlimited iPhone data plan that came with my iPhone 3G in 2008). But the new iPad is different: it’s a 4G device, and the unlimited data plans were 3G plans. That raises a big question: can those happy few who have managed to hang on to their unlimited data plan for two years keep it when they switch to 4G?

According to AT&T, the answer is yes. There is little information on just how many people still have the old unlimited iPad data plan, but those that do get to keep it even when they make the jump to 4G. AT&T will not take it away from them.

Well, AT&T won’t offficially take it away, anyway. AT&T has had a somewhat rocky relationship with unlimited data customers in recent months. Last fall they started throttling the connection speed of users with unlimited data plans after they hit around 2GB of data in a month. This, they argued, was to protect the overall 3G network from the “top 5%” of customers who were supposedly hogging all the bandwidth for everyone else. Despite losing a small claims lawsuit in late February over the practice, AT&T officially announced at the beginning of this month that unlimited data plan users who go over 3GB of data in a month (which, coincidentally, is the highest tiered plan AT&T offers) could expect to have their connection speed throttled.

So, the moral of the story is this: if you’re still rocking a vintage 2010 unlimited iPad data plan, you do get to keep it. But if you actually try to make good on the “unlimited” part, AT&T is likely to throttle your connection. In effect, “unlimited” doesn’t actually mean “unlimited.” It means “about 3GB.”

Do you still have an unlimited data plan? Will you carry it over to your new iPad, or go for a different plan? Let us know what in the comments.