Twitter has announced, after their initial testing, everyone is now getting 280 characters to tweet with:
During the first few days of the test many people Tweeted the full 280 limit because it was new and novel, but soon after behavior normalized (more on this below). We saw when people needed to use more than 140 characters, they Tweeted more easily and more often. But importantly, people Tweeted below 140 most of the time and the brevity of Twitter remained.
I’ve found my brain just skips over most tweets that look “long.”