Microsoft announced Office 15 Technical Preview in January this year. Only select partners were invited to the technical preview under non-disclosure agreements. Some screenshots leaked initially but Microsoft managed to keep technical preview with out any leaks. Today Paul Thurrott of Winsupersite managed to get his hands on Office 15 Technical Preview and posted several screenshots of the next generation Microsoft productivity suite.
According to Paul Office apps have some Metro style design and he says visually it should sit between Metro style and the traditional desktop. There are some new things like a new tab in Word called Design for configuring document themes, watermarks, age colors and borders. If you are interested to see how the nest generation of Office looks like visit his site. I am including some screenshots he posted below. Office 15 public beta will start this summer.