Yammer, a micro-blogging tool for enterprises, launched at the TechCrunch50 conference. This "Enterprise 2.0" startup allows companies and organizations to take advantage of a technology like Twitter. On Yammer, co-workers exchange short frequent answers to the question: "What are you working on?" As employees answer this question, a company feed is created in one central location. The company feed can be accessed in real-time via the web, IM, SMS text messaging, an iPhone application, a Blackberry application, a desktop application, or email. Yammer also serves as a company directory in which every employee has a profile and as a knowledge-base where past conversations are archived. Yammer ensures the privacy of each network by limiting access to those with a valid company email address.