Twitter announced today that it has started testing 280-character tweets for select users . The new limit doubles the current 140-character limit, and is said to help users be more expressive. The Verge reports:The report goes on to note that the "140-character limit was originally established to reflect the length of SMS messages, which was how tweets were distributed prior to the development of mobile apps. SMS messages are limited to 160 characters; Twitter reserved the remaining 20 for the username," reports The Verge.