PlusFeed is a simple service that provides an RSS/Atom feed of any Google+ user’s public posts. Simply find the unique number at the end of their profile URL, and then add it to the PlusFeeds URL. So, for example, the URL of Google Plus Blog's Google+ RSS feed is:
All their public posts will be added to the feed. And the seem to be update quickly.if you’ve been desperate for Google+ RSS feeds – your wish is granted.