The foundation of the business case for open-source is high reliability. Open-source software is peer-reviewed software; it is more reliable than closed, proprietary software. Mature open-source code is as bulletproof as software ever gets.
Consider DNS, sendmail, the various open-source TCP/IP stacks and utility suites, and the open-source scripting languages such as Perl that are behind most "live" content on the Web. These are the running gears of the Internet.
These open-source programs have demonstrated a level of reliability and robustness under fast-changing conditions (including a huge and rapid increase in the Internet's size) that, considered against the performance record of even the best closed commercial software, is nothing short of astonishing.
FOSS.IN - India's largest Free & Open Source Software (FOSS) event, is just around the corner and I'll be there to learn something about some of the interesting stuff that's appeared on the scene lately.
Read The Case of Open Source for Business.