I'm pretty sure this feature is not on by default. You must turn it on in labs and then it is enabled. It's odd if that's the case because everyone posting here

I'm pretty sure this feature is not on by default. You must turn it on in labs and then it is enabled. It's odd if that's the case because everyone posting here knows of it as if it were just part of the experience. But I'm looking at the on/off radio button in labs in another tab right now.