I don't have much to say here, mostly because I don't have any skin in this game (I don't run a twitter client, or even do any twitter integration in anything I work on).
The only thing I find really strange about the announcements is the vague language regarding what kind of apps they like:
With our new API guidelines, we're trying to encourage activity in the upper-left, lower-left and lower right quadrants, and limit certain use cases that occupy the upper-right quadrant.
They waste a diagram and several paragraphs saying "We're totally happy with everyone who isn't making traditional twitter clients". Then, just to make it perfectly clear, they go ahead and spell it out.
Nearly eighteen months ago, we gave developers guidance that they should not build client apps that mimic or reproduce the mainstream Twitter consumer client experience." And to reiterate what I wrote in my last post, that guidance continues to apply today.
Those two sentences are possibly the most passive-aggressive thing I've read all week. It's written like someone trying very hard not to say what he's thinking, hiding behind red-tape phrases like "that guidance continues to apply" in an attempt to sound authoritative.
I understand that they're trying to sweeten what's otherwise a pretty bitter pill for anyone who runs a traditional twitter client, but listing examples of every other kind of way you can base an application around Twitter's infrastructure just seems really condescending.