The original TweetDeck lost its mojo when twitter took it over, imho. Since then, twitter has started to rebuild TweetDeck, and this new feature looks as if it's becoming more useful with TweetDeeck Teams.

TweetDeck Teams is a simple solution to Twitter account sharing. It enables you to delegate access to as many people as you like, and remove accounts when they no longer need access. In order to use this new feature, you must log in to TweetDeck with your Twitter account.

Twitter Rolls Out TweetDeck Teams