Google+ just added a "Feature Update", the new section in added is called "What's new in Google+" and acts as a release notes for any new features or tweaks that Google makes to the service.
An interesting feature of the "What's new in Google+" page is that most of the posts include a video post describing what has been changed. These videos are recorded by the community rather than any official Google body. Google manages to use YouTube for this as it's their own service, and therefore they are promoting one of their services through another service they have. They did the same thing with Google Chrome soon after its original release, with links to their official download page coming in the form of an advert in the search results.
The Google+ community manager, Natalie Villalobos, released a video on YouTube (embedded below) in order to announce the release of "What's new in Google+" page.
Here's the said video:
More Info: What's new in Google+