The new Twiiter anti-phishing service, which launched Tuesday, essentially serves as a proxy between users and whatever sites the links are pointing them toward. When a user clicks on a shortened URL in a Twitter messages, he first will be routed through the new Twitter service, which will inspect the link and prevent the user from visiting the page if it looks malicious.
via threatpost.com
Also, tinyurl gives a preview option as shown in this tweet:
seafsee Dubai tower exporting 10 times more renewable energy than needed (preview) http://preview.tinyurl.com/yeqyomr / http://tinyurl.com/yeqyomrIf you click the preview link, tinyurl will show you what the real link is.