I have a Twitter account under the name mattskala, but I no longer endorse Twitter because their newly-mandatory "OAuth" system treats open-source client software as second class. We were warned about this, and apparently it's been in effect since September 1, but the first I knew of it was a vague awareness that my automatic word counts weren't getting posted. It turns out that now it's no longer possible to authenticate to Twitter with HTTP "Basic" authentication; you must go through the human-readable Web interface, or authenticate via something called OAuth. So it's a lot harder to just send an HTTP transaction with a simple utility, and have an update posted. The API has become much "heavier."
OAuth offers some entirely genuine technical advantages. However, every application used with OAuth must be registered with Twitter, violating the basic principle that it is none of the service's business what software I run on my computer and it is nobody's business whether I am a robot or not; furthermore, open-source applications (unlike binary-only applications) are not allowed to distribute the keys associated with this registration process, but must require users to register themselves per-application and per-account as if they were developers.
This is an unwarranted imposition of control by Twitter over what software can or can't connect to the Twitter service. It probably does not technically violate the anti-Tivoization terms of GPL3 because it's technically a restriction on the service provided by Twitter, not on my local hardware or software. Of course, GPL3 has no jurisdiction over this case anyway - I mention it as an example of the kind of principle that Twitter is working against. Someone could argue that Twitter has the right to make any rules they want about how I use their computers involved in providing the Twitter service. But the newly-mandatory OAuth requirement, and specifically its anti-open-source bias, is definitely not in an open spirit and it is not an act of good faith on Twitter's part.
It would be easy to declare that I'm going to just leave Twitter entirely over this. However, I'm not sure that I'm really willing to do that, in large part because of my current book project. Pretty soon I'm going to have an important business reason for wanting people to be able to find me on social networking; and that does have to mean the popular social networks that people actually use, not some wacky corner run by open-source people where everyone's allowed to show up but nobody actually does. I've already stormed off of Facebook (I fully expect my publishers to try to pressure me to create a "page" there eventually, and I guess I'll let them set it up if they're willing to be in charge of it), and I left Livejournal and cut way back on Dreamwidth, and never even seriously considered getting a MySpace account. I feel a fair bit of pressure to maintain a Twitter account and keep posting tidbits to it so readers have a way to connect to me, even if my main Net presence is in a better place (like this Web log).
So my current plan is that I will keep the Twitter account. I've found a piece of client software, namely TTYtter, that I can invoke from command-line scripts for things like my automatic word count updates and that doesn't require me to install a kitchen sink full of Ruby, Python, and other such foolishness. I will probably also continue posting non-automated comments and random thoughts to Twitter, much as I've been doing.
However, I'm not going to endorse Twitter anymore. I used to tell people that I thought it was a good service. I no longer believe that. Now I will tell people who ask me (and many do) that I don't approve of Twitter's policies, and I will tell them why.
I will investigate alternate systems that provide a similar "microblogging" service - identi.ca is one, though I don't know anything about it beyond the name at this point - and if I can find one or more that I like, I will start posting my updates there in addition to on Twitter. And I may eventually start posting some updates of interest only in the other place(s), to give my readers an incentive to switch.
I'll update this posting with new information (such as alternate services I might decided to use) when it becomes available.