Those weird green decorators in the latest @WebStormIDE tho.pic.twitter.com/lmwU4nzEcd
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
I'll probably get used it it
just took me by surprise at first. And I agree it's useful to differentiate. 
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.