The incident that kickstarted this initiative was the sudden change in Facebook's Terms of Use (later reverted) under which all of the content you’ve ever uploaded was Facebook's to be used in whatever way they want, even if you quit Facebook altogether.
Over 600,000 users participated in the vote. Facebook has around 200,000,000 active users, which means that only 0.3% voted; a very small number if you compare it to, for example, the US presidential elections of 2008, where the overall turnout was 61.6%. Obviously, only a small fraction of Facebook users take the service seriously enough to actively participate in its governance, even if it only takes a couple of seconds to vote.
What does all this mean? Well, the proposed new document should now become Facebook's new Terms of Use. From the official blog: "Assuming the auditors confirm the preliminary vote result in favor of the proposed documents, we'll be adopting the Principles and Statement of Rights and Responsibilities as the governing documents for the Facebook site." Facebook believes that now they can put an end to the Terms of Use turmoil. As Ted Ullyot says on the official Facebook blog, they "strongly believe that our proposed documents satisfied the concerns raised in February."
It's not that simple, though. What Facebook did here is offer two choices; what if you liked neither? The new document was created based on the “comments from users and experts received during the 30-day comment period.” Taking comments into consideration is nice; but Facebook had the last word in the actual creation of the document.
Perhaps this entire talk about the democratic process on a social network seems silly, but once you go that way, why not go all the way? A modern democracy has a lot of tools that are supposed to make sure that the will of the majority really gets carried out; perhaps as a next step in its journey towards a real democracy (assuming that's what Facebook wants) they should consider voting for representatives from the user base, creating a board that will actively participate in the creation of governing documents for the site.