AT&T customers on unlimited data plans can now download a lot more before getting throttled. AT&T has changed its throttling policy so that it'll only slow down a subscriber on an unlimited plan once they've used 22GB of data within a single month, up from just 5GB under the old policy. It's also worth keeping in mind that, as under the old policy, throttling is only supposed to kick into effect in areas currently experiencing network congestion — once the congestion dies down or a throttled subscriber connects to a lesser-used cell tower, they should start receiving full speeds again.
Throttling is allowed for "reasonable network management."
The update makes it a bit harder to complain about the limits that AT&T puts on unlimited data lines (at least, so long as throttling is truly only applied when there would otherwise be network congestion). AT&T hasn't offered unlimited data plans for years now, but many subscribers are still hanging on to the ones they signed up for years ago. As long as AT&T keeps them on as customers, it has to honor its promise of "unlimited" data, something that it hasn't done so well in the past. For about three years, AT&T would cap data speeds regardless of network congestion, which gave subscribers something that didn't look at all like an unlimited plan.
AT&T has since implemented its policy of only capping data speeds when there's network congestion, which is more of a legal requirement than a kindness. The FCC and FTC are both going after it for misleading customers about "unlimited" data — the FCC has even proposed a $100 million fine — and throttling is actually prohibited under the new net neutrality rules. However, "reasonable network management" is allowed, and AT&T as well as other carriers are testing the waters with changes like this to see if they can still minimize problems from heavy data users without crossing lines set by the new rules. It's not entirely clear yet what the FCC will consider "reasonable," but AT&T's new plan is certainly a lot better than its old one, even if it does still single out the unlimited data plan.