SocialFlow, a social media optimization platform, announced Friday that it has raised $7 million in Series A funding led by Softbank, with participation from Softbank NY, RRE, Betaworks, Highline Venture Partners, AOL Venture Partners, SV Angel and several angel investors.

Along with the new funding, SocialFlow also says it has finalized its partnership with Twitter, which grants the startup access to the full Twitter Firehose. That’s over 140 million tweets every day.

What SocialFlow does with that data is helps clients push out their content at the times and days that makes the most sense for each client’s particular audience. The company promises more engaged fans and followers clicking, retweeting and sharing your content more often by boiling the art of social media down to a science. The focus this week is on Twitter, because the company now has the entire firehose at its disposable, but SocialFlow also helps publishers and marketers improve social media performance on Facebook and Google Buzz.

Metrics, insights, analytics--naturally, it all comes standard with SocialFlow.

Both news publication The Economist (@theeconomist) and the New York Public Library (@nypl) offered up glowing testimonials for the press release because each has seen such impressive and tangible growth as a result of using SocialFlow.

The NYPL, for example, says blog pageviews have increased by 30 percent in the first quarter of 2011, versus the same period last year. And The Economist, after eleven months, saw clicks per tweet grow by 150 percent and clicks per follower grow by 50 percent. Its number of followers tripled and referrals from tweets quadrupled.

“SocialFlow is an instrumental part of our efforts to grow an audience on Twitter and drive engagement with our content,” said Dave Humber, manager of audience development, The Economist. “The logic and science behind SocialFlow’s approach was very appealing from a performance perspective, but also as a way that enables us to scale our operations with a relatively small team.”

Based in New York City, SocialFlow is a Betaworks company. Betaworks makes seed-stage investments in new media companies, like SocialFlow, bit.ly, Chartbeat and Tweetdeck.

We now have at least three companies on the books with full access to the Twitter Firehose--Gnip, DataSift and SocialFlow--but each appears to be putting it to use in different ways. This is looking more like the third-party ecosystem that Twitter has envisioned for its data.