It may be that the Chimney Sweep effect is the key to understanding what Google Authority is all about. Most journalists know it pays to rub elbows with all kinds of people at all levels to get the scoop on the latest news, and it appears like Google+ may work the same way.
There are many elements to Search Engine Optimization that may be not fully understood, especially by non-technical writers, however, the chimney sweep analogy can help us understand Google Authority, and what it means for SEO. In that movie everyone watched as a kid, (even if you were born much later than the movie), we learned that chimney sweeps have some kind of magical “dust” that rubs off on anyone who shakes their hand. Authority on Google is somewhat like that.
Ok it may be a simplification, but here’s how it works. There are those who have Google Authority in their particular niche of expertise, and those that don’t. Like the chimney sweeps, anyone they shake hands with, gets a little bit of that “cred”. If you guest post on an “authority” blog that helps you to gain some. If someone with cred=authority, posts on your blog, well, that helps you gain Google Authority as well.