We’ve received great feedback since launching our tracking spreadsheet of Presidential candidate buzz on Facebook, including props from All Facebook, ABC News, and WNYC’s Brian Lehrer Show.

However, the number of people talking about a given candidate isn’t the most interesting number.

What we really wanted to get at was the number of people who might hear this buzz. Mashing up the “Talking About Number” with another recent feature release in Facebook Pages, we’ve been able to come up with an estimate, and have updated our daily tracking spreadsheet accordingly.

The number is staggering: recently, an estimated 230 million impressions of posts from someone’s friend mentioning Barack Obama or a Republican Presidential candidate in news feeds: 140.5 million for Obama, and 89.9 million for the GOP field combined. This includes 24.1 million for Ron Paul, 22.7 million for Herman Cain, and 19.1 million for Mitt Romney.

How did we come up with this number?

The recent upgrade to Facebook Insights for pages includes a telling stat: the number of people who are friends with your fans. Since we administer quite a number of pages for political figures, we decided to figure out how many average friends a politically plugged in Facebook might have. The average was over 350 friends across numerous pages (it was never less than 300 for any page). We think this is also representative of the people who would share content about a Presidential candidate.

If you want to know why everyone seems to know about the Herman Cain smoking ad, viral distribution on social media is a big piece of the puzzle, because the multiplier effect of even a single person sharing it is huge: hundreds of people are now aware that it exists.

Of course, these numbers don’t tell us how many unique people saw the buzz: some friends may overlap, some people may not log into Facebook daily, and some may have stories hidden from the news feed. Even if the real number is half this, that’s more people than voted in the last Presidential election — and we’re just talking about Facebook users.

And, at a very minimum, this research suggests that’s highly likely that the average American Facebook user has seen something about the Presidential candidates from one of their friends in the news feed — and given that a personal endorsement from a friend is one of the most important driver of voting, that’s significant.

This also highlights the tremendous opportunity for candidates to effectively use Facebook and other social media platforms as leverage to gain mindshare among average voters. Ron Paul was able to push up his numbers in recent days through extensive social media sharing of his recent moneybomb. Through the Multiply platform here at Engage, we’ve been working on ways to create structured Facebook sharing calls to action that can generate hundreds of thousands of news feed impressions with just a few hundred people taking action.

As you can tell, we’re very excited about this upgrade to our Facebook tracking, and hope you’ll check it out daily.