If you were to rate the companies that use the most open-source software in their products, who would be top of your list? Red Hat, given that it's a pure-play open-source company? IBM, given its massive investments in Linux and Apache?
Or how about Cisco, with this impressive list of open-source licenses used for software embedded in Cisco's security appliances?
This list includes just the licenses for the APA and PIX security appliances, and doesn't cover the open-source software embedded in other Cisco products, like Unity Connection. It also doesn't address the open-source work that Cisco has done with its new open source-based IP Alliance. All of these build on and other products.
There's also a growing body of open-source code focused on extending the functionality of Cisco's products.
When did Cisco become an open-source company? Hint: it didn't. It has just allowed more and more open-source software to pervade its products, making open source business-as-usual for Cisco (and its wide range of customers). This will be how open source grows: product by product, many of which will have a proprietary veneer but with open source at their core.