Tommy Caldwell has managed to free what could be the hardest pitch of the Mescalito/Dawn wall project on El Cap, Yosemite.

The pitch in question is #15, the second traverse pitch, and according to Tommy it weighs in around 14d/9a. This means it's the hardest single pitch in the valley, and also by all likelihood the hardest traditionally protected route in this part of the universe.

On Instagram, Tommy writes:

...I regret to inform anyone that wants to climb the hardest pitch in Yosemite, now they have to get to the absolute middle of Cap to make it happen.
After years of work PITCH 15 WENT DOWN!!!

Pro Climbers International posted that

...this [...] represents a huge step toward an eventual send of the entire route. "

If we're talking about freeing all the single pitches, this is of course true, but if we by "sending the entire route" mean climbing all the pitches in one single push, surely that will be a while still, don't you think?

If I read Kevin Jorgeson's hand drawn topo correctly, there are four or five pitches of ~8b+ - 8c+, as well as a few ~8a+'s, which have to be climbed before you even get to the 9a pitch. After this follows the pitch with the huge sideways dyno (2,4m?), before you reach easier terrain in the form of a few ~8a+ pitches...

When (if?) this project gets done, arguing against this being the single most impressive climbing achievement of all time, and by a long way, will be rather difficult.