After nearly five years of hoarding and refining nearly a petabyte worth of places data, Los Angeles-based big data startup Factual has been slowly coming out of its shell over the last 12 months. The company has released a number of public APIs which developers can use to tap into its rich stores of information. And it has begun to reveal several of its more prominent clients, including Apple, Facebook, Foursquare, and Yelp.

Today, the company founded by former Applied Semantics co-founder Gil Elbaz is announcing the addition of two new heavy hitters to its advisory board, Clare Hart and Jason Rosenthal.

Hart is an executive who has lead a numerous data-driven companies including most recently leading the turnaround of Infogroup as its as President and CEO. Previously, she was EVP of Dow Jones and Company, President of Dow Jones Enterprise Media Group, and President and CEO of Factiva.

Rosenthal joins the company having most recently served as EVP of products at Glam Media, a role he assumed through the company’s acquisition of Ning, where he was CEO. Previously, he held senior operating roles at AOL, Netscape, Loudcloud, Opsware, and HP.

Factual raised $27 million in financing alongside its 2007 launch from a cadre of investors, including Andreessen Horowitz, Index Ventures, SV Angel, Felicis Ventures, and GRP Partners. Through this round, the company added both Ben Horowitz and Danny Rimer to its board of directors.

Both new advisory board members have worked informally with Factual over recent months, with today’s appointments only making the existing relationships more official.

“Factual has become the center of an incredibly impressive network of companies consuming and providing data,” says Rosenthal. “They have unparalleled opportunities ahead of them to disrupt traditional data businesses and enable a tremendous amount of innovation by making data available to developers and enterprises.”

Hart was more direct in her assessment, predicting, “Factual will change the game in global content aggregation.”

Game on.