Google has rolled out new Google+ Notifications last week. The new +notifications button, now looks like a "bell" with a superimposed numeric indicator.
As you adjust settings for Circles or Communities, you'll notice that the notifications settings are indicated by the same bell icon.
And, once you click on the notification icon, the notification window pops up. Each notification now has it's own card, and new cards have a kind of fly in effect when you first open the window.
The new messages is more subtle and looks like iOS badges--are now separated that you've read from the messages you haven't read yet. There's also a new button "Mark all as read", clicking it will mark all your notifications as read with a new message: "All caught up!"--and they will appear somewhat dimmed. But you can also mark as read a message by clicking the small "x" icon.
And now, your notifications are grouped into New and Previously Read. If you view them all or mark them all as read, all of your notifications will appear below Previously Read and a cute All Caught Up smiley face appears.
Also, when you look at Google+ notifications, you'll see bigger thumbnails (sometimes 4 of them for each message) for any people involved to the left, their name(s) along the top, followed by the action that was taken (+1's, mentions, shares, comments, invitations).
Along the bottom of each notification is space for some text.
Another improvement with the new notifications is the support of "infinite scrolling," so you can continue to read all your messages, and Google remembers your state when you close the tray. Previously, after just a few notifications, you'd have to click the "View All Notifications." With this you'll no longer be able to use the arrow keys to navigate when you click the bell icon, but the keyboard shortcuts start to work when you click one of the messages (you can use j/k, left/right, up/down).
"When you read a notification on one device, we'll mark it as read on your other devices. Likewise, dismissing a notification (with a swipe or a click) does so everywhere, so you can say goodbye to annoying repeats," informs Google.
Also, now when you view your notifications window, the new notifications indicator will reset--"even if you don't act on any of the new notifications, the numeric indicator will not count again until you get another notification." However, those notifications that you saw in your window "but didn't act on" will remain listed there among your new notifications until you click on them or mark them all as read.