The founders of Skype are using a copyright infringement to stop eBay to sell Skype. The VoIP technology (was name as "global index") use in the Skype was own by Joltid, which is still own by Skype founders.
Skype co-founders left Skype (and eBay) to focus on their new Internet TV startup call Joost at 2007. There are news and rumors that the Skype co-founders (Zennström and Janus Friis) interested to buy back Skype from eBay, seems like eBay get a better deal and sell Skype to a group of investor lead by Silver Lake.
Another interesting thing is, Joost remove Mike Volpi as chairman and then Volpi left Joost. Volpi was Index Ventures CEO before he join Skype and Joost, Index Ventures is an investor of Skype and Joost, Index Ventures is also one of the buyers of Skype now, it doesn't sounds like a co-incidence right? (read here and here)
Skype is a software phone service to all users to make free calls through Internet. Skype started at year 2003 and getting popular for its good voice call quality. Skype is available on few operating system like Windows, Linux, Mac OS and some other mobile platform.
Skype is still a very potential software and services.