One of the most-requested features for Twitters mobile apps may be on the cusp of arriving. Muting is said to be among the most popular features in Tweetdeck, the business-class Twitter client that the company acquired in 2011. Third-party Twitter clients have long supported muting. It also lets you mute entire apps, so that (for example) you never have to see another Foursquare check-in on Twitter ever again.