Rel="author" and Rel="publisher" are the solution Google is adopting in order to better control, within other things, the spam pollution of the SERPs.
If you are a blogger, you will be incentivized in marking your content with Author and link it to your G+ Profile, and as a Site, you are incentivized to create your G+ Business page and to promote it with a badge on you site that has the rel="publisher" in its code.
Trusted seeds are not anymore only sites, but can be also persons (i.e.: Rand or Danny Sullivan) or social facets of an entity… so, the closer I am in the Social Graph to those persons//entity the more trusted I am to Google eyes.
As we can see, Google is not trying to rely only on the link graph, as it is quite easy to game, but it is not simply adding the social signals to the link graph, because they too can be gamed. What Google is doing is creating and refining a new graph that see cooperating Link graph, Social graph and Trust graph and which is possibly harder to game. Because it can be gamed still, but - hopefully - needing so many efforts that it may become not-viable as a practice.
Wake up SEOs, the new Google is here
As a conclusion, let me borrow what Larry Page wrote on Google+ (bold is mine):
Our ultimate ambition is to transform the overall Google experience […] because we understand what you want and can deliver it instantly.
This means baking identity and sharing into all of our products so that we build a real relationship with our users. Sharing on the web will be like sharing in real life across all your stuff. You'll have better, more relevant search results and ads.
Think about it this way … last quarter, we've shipped the +, and now we're going to ship the Google part.
I think that it says it all and what we have lived a year now is explained clearly by the Larry Page words.
What can we do as SEOs? Evolve, because SEO is not dieing, but SEOs can if they don't assume that winter - oops - the
You could use a number of tools to determine which advocates are the most influential. Some of the well-known ones are:
Kred
PeekYou
Traackr
MBlast
PeerIndex
Klout
You could use a number of tools to determine which advocates are the most influential. Some of the well-known ones are:
Kred
PeekYou
Traackr
MBlast
PeerIndex
Klout
For these reasons, option two, editing the sitemap.xml, is the better method. It only concerns one file per version of the website, doesn't affect page loading times, and can be easily used with other file types.
Issues
Although this does the job solving the problem for Google searches, this method isn't universally recognized by other search engines like Bing and Yahoo, which still yield consistent traffic, albeit low, but converting still.
Despite the lack of support by Bing, this method is a great stratagem for working with the biggest in the search game, Google. It permits you to do region-specific targeting of your website in search without incurring penalties associated with duplicate or similar content; an SEO win! This can also be achieved on other search engines. Bing, for example, allows you to make such a distinction with a meta tag inserted into the HTML page or make a change to the HTTP headers; a harder solution than Google's, but still recommended.