For all I know, this change might have been live for some time. However, I just discovered it by reading a tooltip. The former Soothe Animal, now Soothe, removes an enrage effect, and it's dirt cheap to cast too.
Dispelling enrage effects have some utility in PVE. However, in PVP, it'll reduce warrior damage by 10% (removing Wrecking Crew, Enrage and Bastion of Defense for the three different specs of warriors) and preventing one of their self-heals (Enraged Regeneration). Don't rely on being able to stop them from healing, though, as they can just wait for their next enrage effect (since it's a passive proc) and use Enraged Regeneration before you manage to get off a Soothe.
It should also be possible to remove Hunter's Bestial Wrath and The Beast Within. Haven't tested it yet, though. It's also possible that just soothing the pet will take care of the hunter too, at least with the way the talent is worded.
There have been a lot of other changes to spells as well, but this one had so far managed to stay under my radar.
Edit: There might also be other enrage effects it can dispel. Owlkin Frenzy is a possible candidate.