A US study (http://pewinternet.org/Reports/2010/Social-Media-and-Young-Adults.aspx) has indicated that younger internet users are losing interest in blogging and switching to shorter and more mobile forms of communication. The number of 12 to 17-year-olds in the US who blog has halved to 14% since 2006, according to a survey for the Pew Internet and American Life Project.
Many users get "filtered out" (they prefer that term, to "banned") from Twitter's search index because they unknowlingly violated one ore more of Twitter's odd Rules that discourage spamming. Twitter does a less than stellar job of making user's aware of these Rules, and an even worse job of clarifying exactly what the rules really mean. It's all very vague. What being "filtered out" means is that your updates will not show up in any searches, hash tag streams, ete. Tweets that mention your name will show up in a search, but not those actually posted from you.
"Twitter hasn’t caught on with students in the way that other communication platforms have. These other platforms don’t really make sense in a classroom. For now, that leaves Wave."
I love Posterous, but I bookmarked this because of something buried deep within Scoble's preposterous, self-aggrandizing comments - the need for an efficient curation service. If that turns out not to be delicious in the future, what is it? Because it sure a heck ain't Friendfeed.