Reading the Skype forum i found an user that has realized a small program to re-enable the “Skype me” mode (the mode that allows to be contacted from all the world) on version 4 of Skype for Windows.
Just extract the program where you want, launch Skype and login. Then open the program and click on “SkypeMe!” button. In Skype authorize the execution of the program and Xenofilia will run.
Notes: i tried the program with Windows XP and no problems, seems dont working with Windows Vista.