Boutique services company MozSource now offers e-mail technical support services for the Mozilla Firefox browser and Thunderbird e-mail client.

It's not the only startup hunting for revenue from open-source projects. Such companies represent a growing number of cottage services springing up around projects such as Mozilla, Linux, Apache and MySQL.

Take, for example, SourceLabs. The Bellevue, Wash.-based company works with Linux based on LAMP (Linux, Apache, MySQL and Perl, Python or PHP), with an emphasis on performance and stress-testing open-source stacks.

Also focusing on LAMP, SpikeSource, Menlo Park, Calif., holds a venture capital pedigree that shows how much Silicon Valley now sees commercial potential from the open-source world. Co-founded by former Oracle exec Ray Lane—and incubated by VC firm Kleiner Perkins Caufield & Byers—SpikeSource is now headed by former Marimba CEO Kim Polese.

Mozilla Foundation President Mitchell Baker said the emergence of such for-profit companies signifies the industry's maturation. "We're very much at the beginning of business models around open-source projects, but at the same time, there are a number of projects that are mature enough to have an ecosystem form around it."

One factor driving that emerging ecosystem: Developers and customers continue to be wary of being locked into proprietary products. This gives startups such as MozSource and SpikeSource an advantage.

"I'm a little uncomfortable hitching my wagon to any corporate vendor because they go through the seesaw of supporting the channel and then not supporting the channel," said LinuxForce CEO Chris Fearnley. "I'd rather be independent of all that."