Over the last few weeks Twitter's scalability problems have been much discussed. Ranging from service downtime, through significant delays in handling message traffic ("tweets"), to features being disabled for hours at a time Twitter has gone from microblogging category owner to potential also-ran.

This is the downside of unexpected success with Web applications – your service will get pounded and every error condition found over and over again. When that happens you will only have a matter of hours or at best a couple of days to fix problems, and when you don’t public sentiment - being the fickle thing that it is - will turn against and away from you.

So it is that Twitter users are now looking and talking about alternatives, and other microblogging players are trying to get their attention.

In Gearhead last week I mentioned Friendfeed, “which aims to aggregate your social networking and blog accounts so you have, in theory, one point of contact with your social network as well as one point to make comments on content and share it using services like Digg and del.icio.us. Some commentators claim it is the heir to the Twitter throne but, while I like the service, I have yet to be completely convinced.”

Another service that has attracted some attention recently is Plurk, which is similar to Twitter in that it routes small messages (like Twitter they are limited to 140 characters), and similar to Friendfeed in that it attempts to integrate with other networking services (instant messaging, Webmail, social networking) to find your “friends.”

One of the long-term complaints about Twitter has been its user interface which, while not truly awful, is definitely very old-school. Plurk attempts to improve on this with more sophisticated user interface techniques, but (and this may be just my opinion) wraps them up in weird colors and what I can only assume are “in jokes” (the service’s logo is what looks like a ham hock with a bone sticking out of it, on legs, and with a wagging tail).

Rather than showing messages (“plurks”) from users and their friends in a simple vertical list like Twitter, Plurk shows messages as threaded conversations in a horizontal timeline. Moreover this view can be filtered to show a just the user’s messages or both the user’s and their friends’ messages.

Mark Gibbs is a consultant, author, journalist, columnist and blogger.