What is the Facebook Like feature?

“Like” is a way to give positive feedback or connect with things you care about on Facebook. You can like content that your friends post or Pages that you want to connect with on Facebook.

How do I get the Facebook Like’s feature on my blog?

Like – This plugin supports multiple languages, gives a number of display options and can be shown at the top or bottom of a post, on pages and on the front page, all based on what settings you select.
Facebook Like Button – This plugin has a nice settings panel that makes it easy to see and adjust how you want buttons to appear.
Facebook Like Button Plugin – We like that this plugin supports a shortcode, which means that you can indicate what posts to include a button on or not, in the post itself. You can also set default global options.

See more details on Mashable.com