The Qt WebKit stuff looks really nice. 40 lines to add a lite but featured browser, and you can have Javascript call C++ and vice versa – so buttons in HTML can start C++ processes, and C++ can modify the DOM directly ala Ajax. Social embedded should be a piece of cake. He showed an app with a contact book showing a small google map for a person based on their address or location. Harder part might be authentication and security.
Just downloaded some of the KDE project to see how a BIG project handles Qt builds via CMake