Linking to infringing content

The law is currently unsettled with regard to websites that contain links to infringing material; however, there have been a few lower-court decisions which have ruled against linking in some narrowly prescribed circumstances. One is when the owner of a website has already been issued an injunction against posting infringing material on their website and then links to the same material in an attempt to circumvent the injunction. Another area involves linking to software or devices which are designed to circumvent DRM (digital rights management) devices, or links from websites whose sole purpose is to circumvent copyright protection by linking to copyrighted material.[4]

There have been no cases in the US where a website owner has been found liable for linking to copyrighted material outside of the above narrow circumstances.
http://en.wikipedia.org/wiki/Digital_Millennium_Copyright_Act