Mark Zuckerberg, the founder of Facebook confirmed the news today. He added that this will be an optional feature where a user has to enable the option and allowing this feature will mean not only you can dislike others posts but others can do that too.
Here is how you can enable the ‘dislike’ feature on your profile:
1) Go to ‘Settings’.
2) Click on ‘Timeline and tagging’.
3) Under the option ‘who can add things to my timeline’, go to ‘enable dislike’ and check the option.
More details here