A significant security vulnerability has been found in Skype that can allow an attacker to download files from your computer.  The only impediment is that the attacker must know the location and name of the file.  But since most computer users have programs installed in the default location, it is easy for the attacker to request sensitive files. 

Therefore this has the potential o being quite a dangerous vulnerability. 

Skype advises all users to upgrade to the latest versions:

• Skype 2.5, release 2.5.*.79 or later
• Skype 2.0, release 2.0.*.105 or later

For more information:  http://www.skype.com/security/skype-sb-2006-001.html