The installer will include the SP for both operating systems, as well as all previous updates since SP1.
Amongst the new features you can find:
- Better Wi-Fi connectivity (as well as a new Wi-Fi connection wizard called WCN = Windows Connect Now)
- Support for non-Intel CPUs (Like the 64bit VIA)
- Support for Bluetooth 2.1 (including BT stereo etc.)
- Support for a new file system called exFAT (sounds like a diet plan to me ) for Flash memory devices
- Hyper-V support for better virtualization
- An improved installer that can remove software and restore the macine to pre-SP2 state
Microsoft would like everyone to install and test the beta as soon as possible, and start sending them feedback. Rumor has it that the proposed release date is April '09.