If you're a longtime Dropbox user, you might have noticed that your Dropbox folder changed a little yesterday. That's because the Public folder is no longer public.
For any Dropbox accounts created after 4 October 2012, the Public folder, once known as the repository for all the weird stuff you regularly share with people or oddball, one-off web sites, is no more. If you happen to be an old school Dropbox user who has an account older than 4 October 2012, the folder will remain public, but sadly you can't render HTML content any more.
For everyone else, the contents of your Public folder are now private, and if anyone visits that Public folder URL, they will just get an error page. Of course, you can still share folders and links, but the catch-all, single link Public folder is gone for good.
The Public Folder [Dropbox]