All WP8 handsets will enjoy People Hubintegration, meaning you can jump right into Skype calls from your contacts list, rather than having to independently open the app.
In this Preview, you'll get all of the Skype basics in the new, modern design along with many of the new features such as integration with the People Hub and a combined contact list with buddies from Windows Live Messenger.
Both the Facebook and Twitter applications for Windows Phone (as opposed to the integration into the Windows Phone People hub) are lacking many features of the web services, and lag significantly behind the official Android and iOS clients when new features are announced.