As reported earlier today Microsoft is highlighting Windows 7 at the PDC 2008 conference. The keynote is still going on, but MS already published the Windows 7 pre-beta announcement. Update: See these new Windows 7 User Interface Screenshots.

Microsoft says that Windows 7 is designed to make everyday tasks faster and easier, and make new things possible for end users. Windows 7 will streamline and simplify the tasks people do most often. Improved navigation, a new taskbar and a streamlined user interface put commonly used resources within easy reach.
Windows 7 will offer more choice in how users interact with their PCs, such as through multitouch gestures. With Device Stage, Windows 7 enables people to get more from the devices they use most often with their PC, such as cameras, phones and printers. Windows 7 also will make it easier to use home audio-video systems and other networked media devices to play music, watch videos and display photos that reside on Windows-based PCs. And Windows 7 will offer more options than ever to customize and personalize Windows-based PCs with styles that match the user’s personality.

Microsoft also demonstrated, for the first time, its new Web applications for Office, which are lightweight versions of Microsoft Office Word, Excel, PowerPoint and OneNote that are used from within standard Web browsers. The company showed how anyone can use all of the Web, phone, and PC versions of Office to edit the same rich document, switching among them seamlessly with lossless file compatibility. Finally Microsoft tries to battle Google in the online office application space.

In addition to Windows 7, PDC attendees received a pre-beta developer release of Windows Server 2008 R2, which will deliver many enhancements to Windows Server 2008, including live migration of virtual machines, power saving capabilities, and developer features to build and host next-generation applications and services.
Via this Microsoft announcement. Right now the PDC 2008 Windows 7 Keynote streams live on this page.