The release includes the following long-awaited feature: Skype extras (plug-in) framework provides a streamlined process to publish extras to the Extras gallery. Users can find, install, and launch extras from Skype client menus and in the Extras Manager.
Please visit: The Extras guide
A lot more! There's new Skype SDP professional partners directory which you can use to view detailed information on Extras and support from the developers. Thank's to Zoverlord for pointing this out.