Any lingering doubts about corporate America's willingness to trust Linux and other open source tools were erased at the LinuxWorld Conference and Expo in San Francisco last week.

In a keynote session, Richard Wirt, general manager of Intel's Software and Solutions Group, asked a crowd of several hundred how many were using Linux to support mission-critical applications and roughly a third raised hands.

In another keynote, Guru Vasudeva, vice president and enterprise chief architect at Nationwide, a $21 billion insurance company with 30,000 employees (6,000 in IT), outlined a Linux-based server optimization project. The company has deployed 350 Linux virtual machines on two mainframes to support 12 mission-critical applications, including the company's Web site and its agency portal.

The system, which supports 100,000 users each day, is expected to save $15 million over three years by reducing Web hosting costs, conserving data center floor space, driving average CPU utilization rates to 70% and maximizing system administrator efficiency. The same admin who could manage only 30 physical servers can now manage 100 virtual servers, Vasudeva says.

Why use mainframes? IBM and Oracle software licenses are less expensive for mainframe environments, and it simplifies high availability and disaster-recovery efforts: One host is used for production and the other for development, testing and disaster recovery, with data replicated every 30 seconds.

Ernest Richardson, project manager of information services for U.S. Foodservice, was at the show to share his experience rolling out an open source CRM project.

U.S. Foodservice, which distributes food to everything from hotels to aircraft carriers, wanted a system to support 5,000 sales people and the company's national accounts teams. That scale put commercial products out of reach, Richardson says, and he was pleasantly surprised to find an answer in Centric CRM, an open source product.

U.S. Foodservice relied on a cadre of players to round out the system, including Corra Technology for development, IBM for the tech stack and SpikeSource for ongoing services. "Implementing a successful open source solution is like building a large puzzle," says Centric CEO David Richards.

Richardson likes the results.

It is real-world experiences like these that have led Network World to create LinuxWorld.com, a Web site that was announced at the conference and is produced in conjunction with that show (Network World and LinuxWorld Expo are both owned by IDG). For a deeper dive on Linux and other open source efforts, visit LinuxWorld.com.