I'll be honest: I understand very little about what's going on with Twitter. I'm not a developer, and my eyes tend to glaze over whenever I try to read the jargon. (Marco Arment has a nice summary though.)
The gist seems to be that Twitter is clamping down on what developers can and can't do with the service, which, according to most, is going to make Twitter significantly less awesome. As a result, my Apple nerd brethren have begun defecting en masse to App.net, a new platform whose Alpha service resembles an extra-geeky Twitter with a $50 entrance fee.
I don't know enough about the issue to judge Twitter's actions. Presumably, they're doing what's best for Twitter. That's their prerogative. If Twitter becomes unusable, it will bum me out. I love Twitter.
But fortunately, App.net has come along just in time to shelter us from Twitter's turn to the dark side. If you're over there, you can find me as andrewmarvin.
As we transition from the old to the new, I'm reminded how important it is not to allow ourselves to become overly attached to anything, let alone a social network. Technology moves quickly. If Twitter becomes something to be abandoned, we will adapt, move forward, and be OK.