Using the authorship tag will get your name and information displayed in the Google search results but that is only part of it. This is not going to be an easy thing to spam because there are obviously many signals such as how much interaction over a period of years, how many shares, the amount of “likes” and how many “followers” you have that make intelligent comments on your Google+ profile. Data bases are collecting this information and Google are seriously hinting that they may use this information.
It may not play a big part in SEO but every little helps and if Google wants to make its search engine about people maybe we should play their game. Only time will tell.
Google specifies that they will not guarantee to display the author shot all the time but I get a 90% display rate.