Has the Apple AI been released yet anywhere?

Some components of Apple Intelligence were release with iOS 18.1, iPadOS 18.1 and macOS 15.1. This, of course, assuming you're in a region that supports it.

You can read about what has been released so far here:

Apple Intelligence is available today on iPhone, iPad, and Mac - Apple

And yes, lots of people have it installed.

And you must own a device which supports it Your tag line says you have a MacBook Air. Your MacBook Air must have a M chip to support Apple Intelligence.

Here is how you can tell if your Air is capable --> Mac computers with Apple silicon - Apple Support