I've seen all the answers suggesting to use other stackoverflow engines or telling it's only for internal use in big organizations like Apple or MS. But seeing facebook.stackoverflow.com & askubuntu.com made me ask this question. Can a big open source project with a huge user base & a developer community get its own stackoverflow site? Maybe not even on its own domain but on a subdomain like projectABC.stackoverflow.com.
If you want to try and get your own site, you can go through the Area 51 process. You propose a site, gain more attention, and eventually, if you have enough of a following, you will reach a Beta site.
Facebook.stackoverflow is just for a specific tag. If this isn't programming related, you can try Area 51.