UPDATE 13TH JULY: The patch notes covering the upcoming Overwatch hero changes are available to read - as well as test on the Public Test Realm.
One general change is that self-healing abilities now charge Ultimates, so the cost of some Ultimates has been bumped up.
Zenyatta's now got 50 health and 150 shields, and his Transcendence Ultimate movement speed has doubled - and the healing increased from 200 to 300 health per second. His Orb of Discord/Harmony projectile speeds have been increased significantly too.
D. Va's Defense Matrix is now bound to your alternate fire button and is governed by a resource meter. It only has a one second cooldown and can be held down for up to four seconds depending on whether it is fully charged or not (charging takes 10 seconds to maximum).
D. Va's Ultimate has been tweaked, too. It no longer damages D. Va when it explodes and takes one second less - three seconds not four - to blow up. Uh oh.
Elsewhere, Mercy's damage buff has been boosted to 50 per cent but no longer stacks with friendly Mercy damage buffs. Mercy can also now move while resurrecting.
Soldier: 76's spread from his main attack now takes a bit of time to reset, which prevents people tapping to shoot more accurately. McCree now maintains full damage at longer ranges, but not at extreme ranges.
ORIGINAL STORY 12TH JULY: Blizzard will forbid Overwatch Competitive Play teams from doubling up on heroes - or tripling, quadrupling, and so on. Blizzard has also addressed Zenyatta and D. Va, two heroes that needed work. Note that all of these changes are now live on the Public Test Realm and patch notes are available. They may change slightly before general release.
"The big thing for Competitive Play is we're going to turn on one-hero limit, so players will not be able to stack more than one of the same hero within a Competitive match," Overwatch's principal designer Scott Mercer told GameSpot.
"It's not going to affect Quick Play at all, but it is something we're going to turn on for Competitive."
Mercer also revealed that Zenyatta will be one of the heroes looked at next, along with D. Va, who we knew was getting some attention. He talked about how they'll change.
"Zenyatta is getting a little more shields, and he goes a lot faster when he uses his Ultimate," he said.
"D.Va's Defense Field, instead of clicking it and it lasting three or four seconds and having a long cooldown, it's now something where you can toggle it on and off and there's a meter that runs that."
Today Blizzard announced new Overwatch hero Ana, who happens to be Ana Amari, Pharah's mother. In Ana Amari's Origin trailer there were also glimpses of two people we haven't seen before, so I got nerdy and speculated about who they could be.