A quintessential success story example, would be JBoss; http://en.wikipedia.org/wiki/Jboss

JBoss (pronounced Jay Boss) is an open source Java EE-based application server implemented in Java. Because it is Java-based, JBoss is cross-platform, usable on any operating system that supports Java. The core developers were originally employed by "JBoss Inc." founded by Marc Fleury. Red Hat bought JBoss for $420 million in April 2006. The company profits from a service-based business model. As an Open Source project, the project is developed and supported by a wide network of programmers.