Microsoft disclosed Windows Server 2008 R2 today at PDC for the 1st time today.  Here is a short summary of some of the new cool features in 2008 R2:  

Virtualization

• R2 Hyper-V  - client virtualization when used with Virtual Desktop Infrastructure (VDI), improved management via PowerShell 2.0 cmdlets, enhanced admin console, and integration with SCVMM
• Live Migration – No downtime to migrate VHDs between Hyper-V servers
• Presentation virtualization - remote apps look exactly the same as running locally, web page login for RAD (RemoteApp and Desktop), RAD control panel to connect to multiple machines

Windows 7 & Windows Server 2008 R2 better together

• Direct Access – no longer will you have to use VPNs, a seamless experience when transitioning between intranet and internet
• Improved RAD (RemoteApp and Desktop) experience – original high-quality audio redirection, multi-mon, video synced, and audio input recording
• Branch Office - BranchCache™ server significantly reduces bandwidth by  caching frequently used content
• Bitlocker on removable drives – keep the data on your USB flash or eSata drives secure

Management

• PowerShell 2.0 – easily remotely run scripts on multiple machines
• More options for power management – Automatically and dynamically reduce the number of processor cores used (Core Parking) and/or their processor speed / power consumption
• AD updates – easily recover deleted objects, easier to perform common tasks
• Best Practices Analyzer (BPA) - built-in for each server role to help ensure proper & optimal configuration

Web

• Full .NET support on Server Core
• Easier administration – manage your SQL databases within IIS, integrated powershell task automation, built-in configuration editor
• FTP enhancements – FTP over SSL support, IPv6, virtual FTP sites

Scalability & Reliability

• 64 physical Core Support – and 256 logical cores support for a single OS instance
• DNSSEC – verify authenticity of a response from DNS

View the Windows Server 2008 R2 homepage at: http://www.microsoft.com/windowsserver2008r2
Download Windows Server 2008 R2 reviewers guide (Beta) for granular details on the changes.