People are often motivated to contribute to Open Source projects by their "right brain" creative and “artistic” side, more than on a financial rewards or career ambition basis.
However, the “left brain” financial and career rewards of being involved in Open Source are tangible in many cases, benefitting both employer and employee, especially when taking a mid-term or long-term view.
Programmers become better by learning new tools, techniques and programming style from brilliant community members. Communication and organizational skills are also greatly improved by being involved in multi-cultural remote communities, where decisions are made asynchronously and most often in writing. Being exposed to quality software all the time, which is common in projects that build the foundation of the Web, also helps us raise the bar on what we consider good software.
All this translates to greater efficiency on the job, greater software quality as well as improved soft skills and team efficiency.
The benefits of contributing to Open Source are demonstrated in many startups and companies, for both employee and employer. If your boss is not convinced of that yet, this talk will help change that!