As we know by this time, Google has been rolling out updated notifications to the mobile apps and now, the synced notifications are getting a card-like UI update on the web too.
The notifications now has a new bell icon, and mainly, the users do not have to go to the community to view the notifications. This change was noticed by a Reddit user, and the screenshot below shows the updated Google+ Notifications.
Thanks to the new GCM, which is now being (probably) used to sync the notifications across devices. The feature might be rolling out to the users anytime now.