Tr.im URL Shortner blamed Twitter for their shut down. (According to Businessweek)

URL shortening means, it take a short string and redirect to the large string URL.That is it works like a third party media for redirecting a large string URL. Tr.im is the leading such URL shortner company on the web. Tr.im which has strong competitator like bit.ly and tiny.url converted large string of conventional URL to a short string. Twitter user use Tr.im for publishing their large conventional link to shortend string that redirected to the original URL This large string was limited to 140 charecter by the Tr.im. But last sunday this Tr.im announced to quite their business.Last May,Twiter quite their business with Tr.im and make bit.ly as their default URL shrtner.Woodward, the president of Nambu, in an interview of late Sunday night said,"I tried that with selected companies that would have a use for it, and no one wanted to pay anything for it, so I decided to just terminate the project."He laid most of blames to Twitter and said,"They're the default, and even if we're better, it won't matter, so what's the point?" he said. "As soon as bit.ly was made the default, the game was over."

But Tr.im announced that, they will not take new request for URL shortening but they will continue the old link until at least Dec. 31.