While some are immediately contemplating the privacy issues involved--a thorn Google will never be able to remove, it seems--the Google+ integration with other Google products so many are calling are starting to sprout.
Now, thanks to a Google+ post by Gmail engineer, Mark Striebeck, we now have knowledge about posts from Google+ appearing in Gmail. Now, this isn't a carbon copy email of a post being made in Google+, at least, not yet. No, this feature informs you about people you are following, offering notifications concerning recent posts they have contributed.
In Striebeck's words:
You can now see the most recent Google+ post that the sender of the email shared with you in the Gmail people widget - see screenshot below.
The screenshot clarifies:
Click for larger image
As you can see, the email was sent from Bella Kazwell, another Gmail developer, to Striebeck. The circled area shows Kazwell's recent Google+ activity, although, in this case, the posts were made on Unicorn. What is "Unicorn," you ask? Striebeck is already ahead of you:
Oh, and before you ask, 'unicorn' is what we nicknamed our internal Gmail test environment.
Hopefully, those are only public posts or posts meant to be shared with the recipiant or oh, boy another privacy stink coming.
Granted, if they are private posts, and the person receiving the notification is only on a "Limited" basis--meaning they can't see non-public Google+ posts, it won't matter if they are notified about recent activity or not, unless, of course, these notifications would allow the "Limited" access to posts they are not privy to.
If that loophole is opened up by the new Gmail notification system, then yes, Google will have yet another privacy uproar on their hands.