Android Wear is keeping up pace with Lollipop goodness as the first set of devices are now getting an OTA update with parts of Lollipop goodness. This could be seen as an important move from Google to make sure a vertical alignment is maintained on all the devices, as it brings the same Android version on the wearable as on their smartphones and tablet lines.
While it is not really clear when the update will hit the other watches, you definitely would not have to wait too long for it as OEMs are not allowed to skin the software on the watch and all of them are in the native Android state as made available. What may take time is moving from square renders to circular ones and that is why could be that Motorola Moto 360 could get the update a little late. The update currently has brought with it some UI and UX changes, bringing elements of Lollipop and its material design language.
The update is being rolled out as an OTA, though if you have a rooted watch, you can push the update via adb so that you do not have to wait for the notification to show up. You can read more about how to do that right here. In case you wish to wait, you will receive the update in the coming hours or days as it is being rolled out in batches.