Another piece of open source software the corporate engineering uses is , which the company chose because "we could extend it and adopt it to our environment," McWilliams said. The company modified the software so that when employees log in, they can access internal Web sites without re-authenticating on those sites, thanks to a certificate VPN provided to the browser upon log-in. "With other proprietary software, we probably wouldn't have been able to do that," McWilliams said.

Google also has what is probably the world's largest civilian video conferencing network, which was built on top of . Even Google's telephony software is open source: The company uses for telephone routing for its call centers.

Interestingly, Google's approach to scalability is not limited to IT. According to McWilliams, the company also runs California's largest private fleet of buses, shuttles that covey employees to and from work. Each bus is equipped with WiFi, so "Googlers can remain productive while they are commuting," he said.

The IDG News Service