Obama sends his first tweet from new @POTUS Twitter account — using an iPhone http://on.mash.to/1QXmDyK pic.twitter.com/aAyl6MituQ
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
@mashable thank you very much! 
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.