Since I cannot get it yet on Playstore, I can't share the release notes. But same procedure as usual, you can download it from the DJI website. The text above the download icon still refers to version 4.2.4 but if you click on it, version 4.2.6 will be downloaded: https://www.dji.com/mavic-air/info#downloads

Already downloaded few hours back, here the notes:

Added compatibility and features for the Mavic Air:
- Added APAS (Advanced Pilot Assistance Systems).
- Added ActiveTrack with multiple subjects identification.
- Added new Boomerang and Asteroid QuickShots (with v01.00.0100 firmware).
- Upgraded Gesture mode to SmartCapture mode (with v01.00.0100 firmware).
- Enhanced Pano shooting with improved image stitching and
effects (with v01.00.0100
firmware).
- Supported the Mavic Air’s internal storage.
- Fixed bugs and updated certain features.

drn3px69 Posted at 2018-2-8 14:57
Already downloaded few hours back, here the notes:

Added compatibility and features for the Mavic Air:

Great, thank you! :-) Thus all for the Mavic Air.

Wachtberger Posted at 2018-2-8 14:59
Great, thank you! :-) Thus all for the Mavic Air.

You´re welcome! Yes, looks that is.
Maybe this "Fixed bugs and updated certain features" involve something for other models...

Has been out for a few days now

I just got it on the Play Store and all the updates are for the Mavic Air