Microsoft has released the first CTP of the Mirosoft Synch Framework.  It think the download page sums it up pretty well...

Microsoft Sync Framework is a comprehensive synchronization platform that enables collaboration and offline scenarios for applications, services and devices. Developers can build sync ecosystems that integrate any application, any type of data, using any protocol over any network.
The Microsoft Sync Framework provides a platform for taking web services and databases offline. In addition, it provides optimized P2P sync of any type of file including contacts, music, videos, images and settings. The extensible framework includes built-in support for synchronizing relational databases, NTFS/FAT file systems, Simple Sharing Extensions for RSS/ATOM, devices and web services.

- Enable collaboration and offline capabilities for any application

- Roam and share information from any data store, over any protocol, and over any network configuration

- Leverage sync capabilities exposed in Microsoft technologies to create sync ecosystems

- Extend the architecture to support custom data types including files

I've known this was in the works for a while and think it provides a tremendous tool set for completing the S+S story.  While still in development, this is absolutely worth looking at if you have mobile or sometimes connected users and want to pursue a S+S strategy.