Talk about being a victim of your own success. Twitter has become my social networking tool of choice, but I wish the service were more reliable. It's just flaked for what seems like the tenth time in the last month, and now only displays the above message when you try and access it. You might regard that as the "this page intentionally left blank" of the web 2.0 world.
Of course the original design inevitably meant that the service is faced with scalability problems, but Twitter hasn't helped matters by providing tools for "weblebrities" like auto-follow (automatically following someone who follows you). Us regular no-hopers, of course, wonder exactly what the point is: if you have 10,000+ followers on Twitter it's self evident that you couldn't give a bugger what any of them are tweeting, which makes the whole thing a rather vacuous exercise to those of us who prefer two-way communications to broadcasts.
I've actually been a member of the open source identi.ca site since OSCON, and while I think it's great that there's an alternative I haven't yet found it compelling enough to be more than an occasional visitor.
Like email spam it's becoming obvious that whenever a new phenomenon arises in the technical world, once it becomes public knowledge the traditional spoilers (marketdroids, celebrities and the like) will climb aboard and screw it up for everyone else. They just haven't realised yet that the rest of the world is just one short step away from telling them to get the hell out. There are a lot of dinosaurs walking around right now, wondering why they are feeling so warm.