Google has been making a number of changes to its services lately, with the unveiling and official launch of Google Photos which was previously part of the Google+ service, and as of today Google has renamed the Google+ notifications drop-down panel to "Google Notifications" instead. Rather than looking at this as a means for Google to begin severing ties to Google+, (which is absolutely not the case) Google is merely using this name change to encompass notifications from multiple services which it offers. Instead of having the notification panel display Google+ alerts only, it also now displays alerts from YouTube as well as Blogger, both of which are also Google services. The name change serves as a way for Google to display a blanketed set of notifications to its users who engage in all of these services as opposed to just the one.
You can now see the "Google Notifications" panel appears inside of just about any Google service including Gmail, Google+, Blogger, YouTube, as well as the main Google homepage or simply a new tab inside of Chrome, and even in the newly launched Google Photos website. This is one more step to take all of Google's offerings on the desktop and transition them in a cohesive, smooth-running machine, something which shouldn't be a surprise with Google's open commitment to unification of their products and services, and also proves Google wants more people to have the ability to engage in comments and conversation as well as content from all of these services through all of these service's web pages.
These changes serve as a benefit to users, as now that the name change is in place and notifications from other Google services have been rolled up into the panel, more users may end up seeing individual comments or alerts they may have otherwise missed if they didn't frequently visit those other Google websites. It actually makes a lot of sense for Google to apply such a change, because having the notifications for multiple services makes things easier to spot, something which users should appreciate. It will be interesting to see if Google implements some sort of control for the user over what appears in the list and what doesn't, or if they'll just keep everything displayed.