It is very important to realise that these are framework demos rather than product UI demos. To illustrate the difference you might compare these videos with the Symbian^3 demo that Nokia recently released, which shows off a Nokia productised version of Symbian^3 (i.e. one that is close to the state in which you will see it in a real device).
These are the first video demos of the implementation of the Symbian^4 UI proposals, which see a Qt based UI (UI Extensions for Mobile, formerly known as Orbit / Direct UI) replacing the existing (Symbian^1 and Symbian^3) AVKON UI. Symbian^4 is still under very active development - it is not expected to ship in devices until this time next year.
Symbian^4 will see a 'flattening' of the UI with a greater degree of 'one touch' UI interactions. For example there will be a four softkey toolbar at the bottom of the screen replacing the current hierarchical menu (Options) / softkey arrangement. The idea is the make the primary commands for any screen / application available with one touch. A drop down menu, for secondary commands, will be available near the top of the screen (next to an 'always-on' back button) and rearranged status area.
Symbian^4 UI Framework Demo - Homescreen
Items of note in this video: variable sized widgets, multiple page homescreen (introduced in Symbian^3), drag and drop widgets between home screen pages.
Symbian^4 UI Framework Demo - Photos
Items of note in this video: bottom toolbar with four softkeys (replacing the menu [Options] based softkeys), side toolbar with four 'buttons', flick (kinetic) scrolling and navigation in UI, image carousel showing previews of previous and next images in 'album', single tap 'direct' UI interaction.