Unfortunately, the status update is meaningless and does not supersede the terms and conditions Facebook set forth when users signed up for their account. Also, continued use of Facebook's service means that they are agreeing to policy updates as stated in the latest announcement.
Basically, users can't back out of a contract they have already signed. And besides, according to Facebook's latest update, they actually still do own all of the content they upload onto its servers for free - they can just use it for any Facebook-related things they want.
The current surge in copyright declaration status updates seems to have been prompted by a notice from Facebook that appeared in user's notification areas saying that it is updating its terms and policies on Jan, 1, and continued use of the service means that users are aware of and agreeing to the changes.
The changes are actually just a rewording of existing terms, made simpler and easier to understand.
One of the copyright status updates making the rounds in light of the "new" terms and policies is worded like this:
"Due to the fact that Facebook has chosen to involve software that will allow the theft of my personal information, I do declare the following: on this day, 28th November 2014, in response to the new Facebook guidelines and under articles L.111, 112 and 113 of the code of intellectual property, I declare that my rights are attached to all my personal data, drawings, paintings, photos, texts etc... published on my profile since the day I opened my account ... Those reading this text can copy it and paste it on their Facebook wall. This will allow them to place themselves under the protection of copyright."
However, cut-and-pasting a few words will not make any difference, and according to the internet's number one hoax debunking site, Snopes, users only have a few real options if they really don't want Facebook using their content:
Decline to sign up for a Facebook account.
Bilaterally negotiate a modified policy with Facebook.
Lobby for Facebook to amend its policies through its Facebook Site Governance section.
Cancel the Facebook account.
No amount of status updates with mumbo-jumbo legal jargon will change the agreement users already signed up for when they created a Facebook account.