I used Tumblr's Private Tumblelog feature as a group board for my personal friends for about 9 months and then switched to Posterous and haven't looked back.<p>Tumblr is perfect as a "deeper Twitter," but its ability to make a gated community feels tacked on, and it's more cumbersome than Twitter's protected tweets.<p>Posterous has the right idea for this use case. You set a single password, just as you would for a game of Starcraft, and then you use the system as normal, which is much less awkward than Tumblr's restriction of gated blogs to viewing only from the posting UI.