People pass these a lot in forums and Twitter. Be careful, not all of them are harmless. If your antimalware app is not set up properly or updated, your PC might get jacked.
Use
http://sucuri.net/?page=tools&title=check-url to check out "shortened urls" that you're unsure of. This free tool will unpack the url and will check with Google and Site Advisor to see if it's an attack site.