This has been going on for a while now:

Ryan Sarver, Twitter’s platform product manager, has told app developers to give up on making basic third-party Twitter clients because the service needs to “move to a less fragmented world.”

In a lengthy public statement, titled “consistency and ecosystem opportunities,” Sarver says, in no uncertain terms, “developers ask us if they should build client apps that mimic or reproduce the mainstream Twitter consumer client experience. The answer is no.”

Some folks are up in arms about this. I find it hard to get excited about it, personally, because I've never used any Twitter third-party clients. does everything I need Twitter to do, and it does it in a clean, simple way.

The case that Mathew Ingram at GigaOm makes—basically that Twitter picked up functionality from third party apps, learning how to foster the site into a social network—is a good one, but it's also not really relevant anymore. I haven't seen a third-party app bring anything new and useful to Twitter for some time now. Ingram fears a "corporate mono-culture" will take hold, that Twitter is out to protect its revenue streams at the cost of innovation. But I think something that Twitter also has to fear is complexity. It's a simple, easy-to-understand service, and while I'm sure developers will always be willing to add a bunch of features and functionality to Twitter, at some point it's going to stop being Twitter. That's the challenge Twitter is facing now.