Great writeup from Josh Wilburne of Twitter detailing the challenges of designing for the 140 character limit across the world. Two major aspects that stand out:

Automatic density-based adjustments

With this in mind, we designed a system that defines two types of written languages, dense and non-dense, and expands the character limit for non-dense languages.

Continuous insight

While I thought removing the UI until it was relevant would help alleviate the stress of the character limit, it ended up having the opposite effect; people were unable to properly plan their Tweet since they had no feel for how far along they actually were.

There's plenty to debate in the final implementation (as there always is in design), but I love the outside box thinking to classify languages, adapt automatically, and to show progress throughout composition, regardless of the language.