DataSift announced on Tuesday that it has raised $42 million in Series C financing to expand into new markets and accelerate the development of its flagship platform, a social media analytics solution used by more than 1,000 companies in 40 countries. DataSift‘s offering lets marketers keep track of consumer sentiment, brand perception and new revenue opportunities across the entire social universe, including Facebook, Twitter, Tumblr and dozens of other networks. The firm boasts big name clients such as Bloomberg, Dow Jones, and CBS Interactive, as well as prominent social technology companies such as HootSuite and Simply Measured.

New investor Insight Venture Partners led this week’s round, earning co-founder and managing director Jeff Horing a seat on the DataSift board. Existing backers Scale Venture Partners, Upfront Ventures, IA Ventures, Northgate Capital, Daher Capital and Cendana Capital participated as well, bringing the company’s total funding to an impressive $70 million.

“Social is generating billions of conversations every day and that data is fundamentally transforming the way companies communicate and make strategic decisions,” commented Rob Bailey, the CEO of DataSift. “Social has now moved from mainstream to mission critical for enterprises and we are excited to power the applications in the social ecosystem and accelerate social data adoption.”

DataSift is among the handful of companies with full access to the Twitter firehose, a real-time stream of social interactions that averages approximately 500 million tweets per day. Topsy, another member of this exclusive club, was just acquired by Apple for over $200 million. The consumer electronics didn’t disclose its motives for the buy, but one strong possibility is that the startup’s technology will be integrated with Siri to provide a more natural and personalized experience for mobile users. Topsy’s software could also be used to help Apple partners target customers more effectively via iTunes and iAd.