I've built a few small toy apps on Twitter in the past (particularly back when the API was very simple web requests and it was trivial to even use it from shell scripts), but the unpredictability of Twitter toward developers who build things that make money has guaranteed I never took it seriously. Having your business ripped out from under you because Twitter decided they wanted to do something similar is a pretty sad thing.

I'm currently building something that does rely on Twitter, and I'm still hesitant to spend much time on it, because who knows when Twitter will decide that what I'm doing is part of the "core experience" of Twitter and pull the plug on my API access?

Having access cost money isn't a huge problem, as long as it's reasonable, and right now, the costs aren't a concern for my project (I pull very limited data; a few thousand tweets a day). I don't even mind them saying, "Don't do these things with the API." as long as those things are clear and not a moving target. But not knowing when/if Twitter is gonna kill your project is a huge problem.

I'm really not sure the signals I'm reading from Jack and the Twitter folks alleviates that concern. They wanna address pricing, great. They acknowledge that growth is dependant on a twitter developer ecosystem (as fueled Twitter's initial growth), also great. They even acknowledge that they treated developers poorly along the way. Again, great.

But, are they really committing to not screwing people over again?