I dont use short url, if you want to write more than 140 character for your twitter msg, its also possible with tall tweets http://www.exinkai.com/forum/progra...2835-tweet-with-more-than-140-characters#2835
Short URL's are better for the following reasons: 1) You have more space to provide a description/headline of the link (very few will click on a link without knowing what it's about) 2) It leaves more space for retweets (something important that most probably don't think about) 3) Some of the URL shortener services such as bit.ly provide statistics on clicks and such As far as I know, if your URL is over a certain amount of length, it will get automatically shortened by Twitter anyway.