Twitter for the first time in its history is changing its character limit. Anyway at 280 it is double what Twitter offers now to its users and this test service will be made available to a test group which tweets in certain languages like English, Spanish and Portuguese.
The news was announced on the Twitter blog which said the reason for the change was that more characters would give the opportunity for Twitter users to convey a thorough thought in 280 characters instead of cramming it into 140 characters. They found that languages like Japanese, Korean, and Chinese can convey about double the amount of information in one character as in other languages including English, Spanish, Portuguese or French. This means people who tweet in Japanese, Korean and Chinese can express thoughts in fewer characters with more room to spare, as opposed to English, which takes up a lot of tweet real estate
Given this will have core design changes it will take some getting used to for hardcore twitter heads but, will probably get used it.