How many billions is open-source software worth?

Computerworld asks how much open source software as a whole is worth: “Open-source software is big business. For example, most of what Oracle is getting for it $7.4-billion purchase of Sun is open-source software. Thanks to a Linux Foundation study, we know that creating the Fedora 9 Linux distribution would have cost $11.5-billion in conventional software costs. So, given all that, what do you think OSS (open-source software) as a whole is worth? How’s about $387-billion?”