The update is version number 174.44.1 and it has been reported to be pushing out to US and UK models of the Moto G, but should be rolling out to the rest of the globe soon enough. On the change log is a fix for a bug that had been causing cell signal loss for users, a fix for low call volume, a wallpaper cropping issue, and a trouble with USB on the Go.
The cell signal loss issue has been one of the more troublesome issues. We have also heard reports of SMS sending and receiving issues, so we're hoping that this update will fix those issues as well. The update is pushing out now, so if you have a GSM version of the Moto G, you should see it soon enough.
source: Android Police