It's not just Nexus devices that are getting updates right now. Android Wear devices are getting an update as well, but it's just a security tweak for most of them. Motorola's current watches are getting a more sizable update, though.
According to Motorola, the 360 gen 2 and 360 Sport will see the following changes when the update hits.
- Moto Body enhanced calorie calculation: Moto Body now takes heart rate into account when calculating calories burned.
- Moto Body heart rate continuous measure: Heart rate measures in Moto Body are now continuously updated, you don't need to tap to re-scan while you are in the app.
- Security updates: Includes the updates of Android monthly security bulletin until May 1st 2016.
- Stability Improvements: Includes changes that fix bugs and improve stability.
Other watches are getting an update as well, but it seems to just add security patches. The security patch level is also shown in the settings now. If the OTA hasn't hit your watch yet, it shouldn't be long. It's been rolling out for a few days.
- Andy Stetson and Alexander Hentschel