There is a very simple question that Little Bird, a service that launches today in private beta, attempts to answer: What community are you interested in? With that as a starting point, the service chugs through Twitter streams, blog posts and LinkedIn pages to find the most influential people, companies and reading material on your chosen topic.

Started by former TechCrunch and ReadWriteWeb journalist and consultant Marshall Kirkpatrick, Little Bird was born from a need on the part of his corporate clients to know which people and sites were important to their businesses from a public relations and marketing perspective. “They all wanted to know who they should have on their radar when it came to the social web,” Kirkpatrick says. With some elbow grease and hacks, Kirkpatrick was able to answer their questions.

When EMC-acquired data analytics company Green Plum came knocking for the same answer, Kirkpatrick finally built a system that could automate much of his manual labor. Little Bird, formally known as Plexus Engine, came out of that effort.

In a similar way that Google’s Page Rank looks for connections between web pages to determine relevancy, the Little Bird engine analyzes the connections between people to determine who has the most influence in a particular community or on a specific topic. “I like to think of it as a robot librarian that goes out and tackles the social web,” Kirkpatrick says. A Little Bird search will also surface what people are reading and watching, who is the the most active on the social web, and who has the longest track record.

A search on the top influencers in the Apple world leaning heavily on Twitter data yields Apple Marketing Chief Phil Schiller, iOS boss Scott Forstall and the Unofficial Apple Blog as the expert sources to pay attention to. Interestingly Schiller and Forstall barely Tweet. “But they are the ones who the other insiders follow, waiting someday I guess for them to start tweeting, so those two show up at the top of the results,” Kirkpatrick says. Showing some of the gaps apparent in the nascent service, missing completely from the Little Bird results is Apple CEO Tim Cook – most likely because he doesn’t have a Twitter account at all.

Kirkpatrick has raised an initial $1 million in funding fromMark Cuban and other investors to put some muscle on his social search engine. He plans to market it initially to public relations and marketing professions, selling monthly subscriptions offering unlimited access for anywhere from $50 to $2,500 depending on how many people are using it.

As to the question of whether Little Bird will promote a frenzy of self promotion by those dying to be deemed top influencers, Kirkpatrick doubts it. Because a site or person’s rank is determined by how many other influencers follow their tweets or stories it will be hard to game Little Bird. “Besides, no one else is going to see the results of your query, so I don’t think it’s going to end up being a weird public popularity kind of thing,” Kirkpatrick says. “Look, if I was just looking for a random self promotion I would have stuck with writing awful pieces about the future of technology.”