Yammer is an instant messaging tool that promotes short frequent answers to questions within companies.  Yammer serves as a central location for co-workers to exchange ideas, post news, share links, ask questions, etc.  Anyone in a company can start a Yammer network and invite other colleagues.  The company was founded by David Sacks and won the top-prize at the TechCrunch50 conference.

Yammer spun off from Geni.com, another company that Sacks founded.  Geni.com raised $5 million in Series C earlier this week.  The companies involved with Yammer’s $5 million Series A investment were Founders Fund and Charles River Ventures.  The Founders Fund are a group of investors where many partners are formerly of PayPal.  David Sacks was COO of PayPal at one point.

What puts Yammer at risk is Twitter’s ability to launch a groups feature.  If Twitter creates an enterprise version of their service, they could take on Yammer head-on.

[via TechCrunch]