Winbeta's Exclusive Review
Winbeta has an exclusive review of Longhorn 5048 Build (Presented at WinHEC). Along with other new features, two most important and striking features are DWM and Redesigned Start Menu.
DWM or The Desktop Window Manager is a component that manages window policies, behaviors and visual appearance.
Redesigned Start Menue
If you're like me, your programs menu has no doubt become a massive, unwieldy list of programs, with multiple panes on the fly-out menu. That's a real nuisance. In this build, a scrolling list of your programs is built in a subwindow on the left side of the start menu. Also, a small dialog entry box lives at the bottom of the start menu.
If your list of applications is very long, just start typing an app name in this box. As you type, Windows will make a guess as to the name, making the scrolling list shorter as you type more letters. It's a great boon for users with tons of programs.
For more info. have a look at link provided.