One hacker was able to go around - apparently without much difficulty - Skype security systems to easily get the IP address of any user connected. For most people, it is not that big of a problem, but other people need more confidentiality and this new security breach might keep them from using Skype until the security problem is solved..
This page shows that the breach is perfectly usable:
As a reminder, thanks to the IP address, judicial authorities can get the precise location and address of a device and for the rest of us, with rather simple tools, we can have a rather precise location. A hacker could launch an attack against that device using the IP.