The update — software version 4.16.1540.8, if you're interested in such things — weighs in at 584 megabytes. The official changelog reads thusly:

If you've got the developer or unlocked edition of the HTC One M8 , check for a system update. Android 5.0 Lollipop is now available.

Android 5.0 Lollipop update

Lock screen and notification: New Lollipop UI style with enhanced privacy features

Recent apps: Supporting multiple pages

Addition of search function within settings

The update was confirmed by HTC, which said it should start pushing "tonight." Obviously, however, we're seeing it a little sooner than that.

HTC One (M8) Unlock and Dev Owners! We have received TA from Google on Lollipop + Sense 6. OTA will be out starting tonight. #HTCAdvantage — Mo (@moversi) January 13, 2015

We're loading this update as we type, so stay tuned for what's what. For more, be sure to swing by our HTC One M8 forums!

Thanks, Andre, for the tip!