Skype users - does anyone use this on ITKE? - or is it overhyped?

Recently I posted a question about using Skype in a corporate environment. Based on the lack of any feedback, it really makes me wonder if Skype is an overhyped solution for corporate environments. I also posted the same questions to another professional mailing list I subscribe to and received only one (very good) response from that peer group.

So, to be redundant, I want to ask you blog readers the same questions. If there are no responses, then I will take this to mean that either your organizations do not use Skype or that you would rather not share poor experiences. I would appreciate feedback either positive or negative about using Skype in corporate environments.

As is true with most organizations today, we are under pressure to reduce costs where we can. Some users are coming and asking why we are not using Skype for international calling. I’m not sure if I fully understand the risks so I am posting this question here on ITKE.

Has anyone implemented Skype for their organization and is supporting it on company networks and equipment? If not, why not? If you have implemented Skype services, some additional information would be useful.

What precautions were required before implementing this service/application?
What has network usage been like since implementation?
What configuration changes at the firewall (both edge & client) were needed to support the application?

Please feel free to share any other advice you may have about this type of service/application.