SkypeKit allows desktop applications to integrate Skype functionality into partner applications while the Skype desktop API allows developers to extend the functionality of the Skype client.
SkypeKit was originally rolled out in June to help Skype in the consumer electronics industry. Skype developers have been working to improve SkypeKit since and today released a developer preview of SkypeKit 4.02. This new version does bring video APIs to "SkypeKit for Desktop", so that developers can build in native Skype functionality into their own applications for handling video calls. There's also a new "Skype App Directory" that's being rolled out too.
SkypeKit is available for Linux, Mac OS X, and Windows operating systems.
More information can be found from the Skype blog and the Skype developer web-site. Maybe now we'll see Skype support come to the Farstream audio/video framework and other Linux desktop applications.