SkypeKit is described as "a collection of software and APIs that allows Internet-connected devices or applications to offer Skype voice and video calls. SkypeKit is designed to work with a wide variety of chip sets, operating systems, and audio/video devices." SkypeKit is much more in-depth than the previous Skype API that was exposed to third-parties.
SkypeKit is currently in a limited beta program, but on the 23rd of July more invitations will be sent out to developers. SkypeKit can be learned about from the Skype developer area. As we understand it, SkypeKit is just the beginning of a more open Skype VoIP platform and in the coming months more of their intentions as it relates to Linux should be reported.