I hope it never comes back....
I can't deny Skype's utility as a piece of communications software, but from a corporate security viewpoint, Skype is a nightmare ... the protocol's desire to be un-categorisable (random ports, encrypted payload, constantly changing peer IP addresses) is the cause of many security headaches. Session analysis takes forever because of this, and more often than not the suspect traffic turns out to be Skype....
Please Skype - use a standard VoIP protocol, or make yours consistent and distinctive. If not for security reasons, do it so that we can categorise it as real-time traffic and prioritise it accordingly!