The interesting thing about Twitter is that the length limit is artificial (as opposed to text messages where I gather it's more a fundamental limitation of some underlying protocol), and it will allow you 140 characters regardless of how many bytes each character uses. So one can actually pack quite a bit into a tweet using CJK languages.

My observation is that English tweets tend to be a single sentence or at most two, maybe with some tags on the end, but Japanese tweets are often complete paragraphs with 4 or more sentences, sometimes more like little mini-essays—and I hear Chinese tweets can border on the epic...