I have no way of knowing if this was rolled out to 100% of users, or if they updated their embedded tweets to use the font.

But more importantly I just want to see a side-by-side comparison.

Not only that, but when they inevitably change the font again, it would be nice to be able to read a then-old article to see what the font looked like when it was announced.

Must depend on your device as the tweets are using Proxima Nova for me.

edit: although if I click into the tweets and view them on Twitter, it then uses Chirp.