'While a decade ago, home wireless networks were nearly non-existent, 61% of US homes now have wireless access. As a result, a single IP address usually supports multiple computer devices – which unlike traditional telephones can be operated simultaneously by different individuals.
Different family members, or even visitors, could have performed the alleged downloads. Unless the wireless router has been appropriately secured (and in some cases, even if it has been secured), neighbors or passersby could access the Internet using the IP address assigned to a particular subscriber and download the plaintiff’s film.'
Perhaps this will help to stem the tide of frivolous mass lawsuits being brought by the RIAA and other rights-holders where IP addresses are the bulk of the 'evidence' suggested.