Useful.

"The revelation that VoIP traffic can be used as a covert control channel for a botnet is just one more security worry for Skype."

Skype is loaded with issues and flaws , and the quality of the call is really craptastic , people get dropped on the call often especially when on a conference call where one user is on a cell phone.

see also:
http://www.conferencecallspot.com/2008/11/skype-drawbacks-botnet-hack-threat.html

and

http://www.conferencecallspot.com/2008/08/skypecast -teleconference-servive.html

Everybody knows Skype. Among the offerings, Skype provides ability for conference calls with multiple participants as well. You can even have a conference call with people using Skype and people using phones and mobiles at the same time, so you can get all your buddies together on the same call, whether theyre using Skype or not. With Skype, you and 25 other people can take part in a conference call.