Whether it's good or bad to know that someone's connected to you in some way is debatable. We doubt someone engaging in civil discourse in the comments would want a violent person who vehemently disagrees with their views regarding hot-button topics like politics to know that they live nearby. Facebook said the tags will only show public info you can already see if you happen to go to someone's profile, though, and anything a user had set to private will remain hidden.

The feature is part of Facebook's efforts to make public discussions more meaningful. "Knowing shared things in common helps people connect," the spokesperson told Engadget. "We're testing adding a 'things in common' label that will appear above comments from people who you're not friends with but you might have something in common with. Only information that people made publicly available on their profiles will be eligible to show up."

Like any other experimental feature, "things in common" is only available to a small number of users right now, and only in the US. Also, not all experimental tools end up as actual features. Facebook might also implement changes -- perhaps a way to prevent the tag from displaying certain info you don't want to make so readily available -- if ever it decides to release this particular one.