As you've might heard, Microsoft announced its latest generation of mobile operating systems, called Windows Phone 7 Series. One cool thing is that it was something unexpected as where Microsoft would go with its developments, how much iPhone would influence on their UI, whether it would reminicent the Zune Phone idea to some extend. The importance of that annoouncement could not be underscored as it clearly indicates the trends of nowadays interfaces.
Most importantly, systems are moving away from unauthentic 3d interfences whereever possible to the specific areas such as games, TV, AR, i.e. places where it naturally blends with the actual reality and humans expect those interactions natually to be supported by the computers. One can observe that by looking at latest web site designs, e-devices (kindle etc.), mp3-players. Moreover, people would like to offload the thinking about the process and rather concentrate on what is in their current focus and context, therefore, UI is presenting a very few choices to a user at a time in bold annotated graphics, which is clearly seen on iPhone and Zune. People then naturally interact within a context of a device through tough-based interface with system reacting to a user activity immediately through animation and other visual effects. Note that no complex visuals are required at this point as humans are accustomed to a very simple response, usually just affirmative reaction, or, a simple denial of an operation. Furthermore, response on a user action is as simple as visual or audio activity executed by the system. A person is interested in a very few contexts at a time, such as phone communication, social communication (facebook, communities), audio (music, podcasts, lectures), visual (movies, clips), planning (calendar, notes). Microsoft came up with the list of those contexts, which are available in the main menu. Very clever idea is to get rid of task bar at all as it is becoming an obsolete concept nowadays. Widget architecture is a very straight-forward way to extend the device's functionality, because it would give very rich functionality to developers hands and at the same time allows to isolate system's core modules for platform stability.
All at all, the direction where the system interaction with human is moving is clearly set by two major players on the market, namely, iPhone and Microsoft, and with the hardware manufactures's support, the future of the mobile devices looks very promising.