(... achieve Debian world domination without endorsing Facebook)
Yes Raphael, we can.
Nobody said it would have been easy, to reach Total World Domination endorsing Free Software only, but that's not a reason to stop trying.
I've recently stumbled upon a very nice article by Benjamin Mako Hill, titled Free Software Needs Free Tools, which I believe it's the best possible commentary to the proposal of having an official Debian Facebook page.
Of course there is nothing wrong in having non-official, or let's call them "fan" pages, about Debian on Facebook. As a matter of fact we already have one, as you point out. And I also agree that it would be better to know who is behind that page. Individuals, including Debian Developers, are obviously free to use whatever media they please to spread the cause of Debian. After all, as individuals, each of us decide upon her own personal trade-offs (for instance, a trade-off of mine is to have both identi.ca and twitter accounts and to post only to the former with forwarding to the latter).
There is no way to have an official Debian Facebook page and pretend that we are not, de facto, endorsing Facebook. That's why I believe having official Debian presence on Facebook, or on any other non Free Software platform, will just weaken our cause. It will send out the message that Free Software it's something which is good for others to use, but not necessarily for Debian as a project.
That does not mean that we live under a rock and that we consider social networks useless to promote the Debian cause. It just mean that we should be picky in choosing social networks that respect our Free Software principles, as we are picky in choosing licenses that are DSFG-free. For instance, I'm glad to mention here that the Debian publicity team has recently obtained access to http://identi.ca/debian and will start using it soon. Subscribe!
PS This post also gives me a chance to comment on a so called "community page" of mine on Facebook. As I've briefly commented a few days ago I've nothing to do with that page. TTBOMK its content is just automatically injected from Wikipedia. The "Stefano Zacchiroli is on Facebook" claim on the upper left is true only in the sense that there are other people with my name on Facebook. IANAL, but such a claim (not the page in itself) will probably be considered an abusive advertisement in many countries around the world.
update: re-word the
identi.ca/debian paragraph, to better blend with
update: mention "Debian" in heading