The latest "Orcas" CTP includes:

• Microsoft Synchronization Services for ADO.NET
• Provides an application programming interface (API) to synchronize data between data services and a local store. The Synchronization Services API is modeled after the ADO.NET data access APIs and gives you an intuitive way to synchronize data. It makes building applications for occasionally connected environments a logical extension of building applications where you can depend on a consistent network connection. For details please visit http://go.microsoft.com/fwlink/?LinkId=80742 .

Over the years "offlining applications" has been a common challenge for ISVs - and here we are with an extension to ADO.NET for just that scenario.

One of the dev team has a great blog on Sync Services at http://blogs.msdn.com/synchronizer/default.aspx . We also have the documentation available for download (17MB)  if you would rather not install the "Orcas" CTP (Many GB).