Is AS 4.0 a new thing? I just saw happened to see it today

Yes, it was released today https://developer.android.com/studio/archive

well, the Canary

any release notes?

For the best experience developing with Jetpack compose, you should use the latest version of Android Studio 4.0. That’s because when you use Android Studio to develop your app with Jetpack Compose, you can benefit from smart editor features, such as New Project templates and the ability to immediately preview your Compose UI.

Uhh.. is preview available right now??

no, no, read the quote I sent

It was just announced in live stream on Android Dev Summit

Wow, I need to stay more up to date 🙂