Um.. I am using the Camera button.
Oh, yeah, I'm sure a lot of people are, but I'm seeing a lot of screenshots from people who aren't.
I...did not know about this.
That probably would have saved my game from crashing when I tried to screencap a Jigglypuff I saw in the wild earlier this week. And I would up one Jigglypuff!
Incidentally, I was saying elsewhere that I enjoy how this game revived the "schoolyard" style of game design, where the game gives you little in the way of instruction and players learn about different elements of the game by sharing their experiences. It enhances the type of community game that Pokemon Go is supposed to be.