No - it doesn't. You might want it to, but it still doesn't.
OFTEN it does - but it's not a default. If you take a picture of a tin of soup, there is a hierarchy of possible ownerships, or splits of the ownership of that picture. It depends on how you assert your rights, how the manufactuer of the tin of soup has set up their company, and from what country they did it, how they registered their trade marks and image rights etc etc.
If you take a picture of me, and I'm fine with you doing that, then you implicitly own that image. You can go forth and make merry with it as you see fit. But... I can select to assert rights over that photo - becuase it's a picture of me. If I sign a release form, then you do have rights.
If I choose to, I can take a picture of myself and submit it to any image hosting website, and class the picture as "Creative Commons" - Creative Commons has a derivate works section to it - which would suggest that any future pictures of me - lets say you get a picture of me next year - would also need to be issued under creative commons as well. In theory, you are prohibited by law from even attempting to put a "copyright Joe Bloggs" banner on it.
If you take a picture of many federal buildings in the states, the US government owns the image rights. If you take a picture of a painting in a UK *public* art gallery which is owned by the state, and you are a UK citizen, and the artist has been dead longer than 50 years, you can do with the image as you see fit. But if that image is on loan from a private collection, then the IP belongs to the owner of the original picture, no matter what the vital signs of the artist.
The reason for all of the point examples above is to re-emphasise the point I tried to make. There is a HUGE amount of legal structure in place around the concept of copyright. There is a hierarchy of laws. These are also dependant on the subject of the photo, the ownership of that subject, your nationality, the country you took the photo in etc etc etc etc etc
To make such as sweeping statement as "I own the copyright" is generally going to be incorrect. At best you can say
"I *think* I own the copyright, and in general, no one is going to make a fuss unless my picture is worth millions, at which point, the lawyers will have to thrash it all out"
f its not their copyright in the first place (how many photographers sell the copyright with photos, not many) how can they give permission for facebook to use it? hence the report button and the "How to report claims of intellectual property infringement" page here -
http://www.facebook.com/legal/copyright.php
That doesn't matter. The image has become facebook's. Which is why I said about the small claims court - If I upload a photo that you took to facebook, then it's facebooks. You can look to me to make restitution to you, and facebook probably will look after you and take down the image - but they don't have to.
<<edit...>>
The last two posts talk about "permission" - that permission for copyright to be moved around is granted.
There is a huge muddle of laws regarding this, and generally there is no fully accepted common law on it. Which means it all comes down to contracts. If you haven't signed a hefty contract, your likely not protected as much as you think. When you sign up for facebook - as an example - you sign up to a 6,000 word contract, with more than 1/3 of that talking about IP ownership.
Again - I say this to raise the point - just becuase you assume, or would like, copyright to work in a certain way, one that to you feels fair, then it doesn't mean a thing. Only contracts written by lawyers mean much at all, and even then it's going to get messy in a court if someone really does care.
I'm not saying that I agree with this system - I don't. I work in software design, and it's even worse in that world when it comes to copyright and patents than it is in the world of pictures - which is why we have a group of lawyers on the next back of desks to our development teams. I'm just saying that lots of lawyers get very rich from copyright law, and rich lawyers ALWAYS means that something is very complicated.
I will ask one of the legal eagles that I work with to sign up for this forum and write some sort of "your basic rights for copyright" if anyone wants me to?