But it's fantastic interaction design all the same. It's this attention to detail, this relentless drive to add just a little more delight or remove a little pain, this tendency to never be satisfied with the status quo that can lead to great things.
I use this all the time. In fact, almost every time I upload a photo to Twitter, it's via that button.
It wasn't difficult to add that button. All the developer's had to do was give a damn.
Update: My friend Jason wrote in to tell me it was actually Nevan Mrgan who suggested the idea last November, an idea to which Tapbots credited him.
I guess in addition to giving a damn, it also helps to listen to your users. Turn out.