On June 27th 2012 Microsoft accidentally put Skype into thier ‘Important’ updates for the WSUS. What happened was that millions of users got Skype installed on thier desktop without consent and let’s face.. not really needing it.
The update was ‘expired’ once the error was discovered but the fact it happened at all is rather disconcerting. Not only was the program installed without user approval (being it was misclassified) but it makes this vector of program installation much more suspect.
The long and short is; if you suddenly have Skype on your desktop you can uninstall it. It was a Microsoft error that put it there and with luck it will not happen again.