Twitter engineer Nick Kallen posted a tweet late Wednesday night to highlight a new test feature that the microblogging service is working on.
"We're testing the 'You both follow' feature (in the profile sidebar)," Kallen wrote. "Only 10 percent of people have it for now."
Basically, this feature (if it ever takes off--loads of test features on social-media sites never see a full launch) will let you see, on a random Twitter user's profile, whether there are any Twitter accounts that both of you follow. If you follow lots of people or companies or news outlets in common, presumably you might have something in common with that user as well and might want to follow him or her in turn. Or more likely you'll be exposed to.
The announcement of a relatively small feature like this is likely to set off speculation, considering the feature's resemblance to Facebook's longstanding "friends in common" feature, but it's more likely designed as one of a series of minor upgrades to the Twitter.com interface. Critics say that Twitter's own Web site lags behind the experience of many of the third-party clients developed for the service, something that Twitter is now .
The test on a small portion of Twitter's user base will likely give the company an indication of whether it actually does much of anything to build follower counts and user engagement.