According to Peter Kafka at All Things D, Yammer—the Twitter for work—is looking at a rising sun this investment cycle,

Chatting at work is serious business for Yammer. The two-year-old start-up has raised a $25 million funding round led by U.S. Venture Partners, complementing the $15 million it has already raised to date. Yammer offers a social network for enterprise customers, and has plenty of competition from the likes of Salesforce’s Chatter, Socialcast, etc.

Ev Williams, the co-founder of Twitter, says that he spends more time on Yammer than he ever does Twitter. As a little workplace communication powerhouse allows for extremely niche conversations, which makes it ideal for the business. First there’s memos, then there’s e-mail, then there’s Yammer.

According to sources, this raises the startup’s total funding to $40 million.

It’s no surprise they’re growing so quickly. The social networking platform provides for a lot more than just microblogging and instant messaging but also polls, links, topics, ideas, and other meta-content contingent on how subscribers inherit and digest information from one another.