It is said that RIM has added system-wide kinetic scrolling with rubberbanding to make flick scrolling much more fluid. A pinch-zoom function has been added system-wide.
The homescreen is said to be fully customizable to allow pages, but widgets were not initially seen. BGR also said you are able to slide from side to side to see more applications (similar to iPhone and Android OS). You can also set different pages for your home, favorites, all, etc.
The release of OS 6.0 is said to officially be in the market around June/July 2010. If so, it should be highly likely that we will see a nice OS 6.0 presentation at WES 2010.