If you haven't seen it yet, the Sync Services CTP was released a couple weeks ago. Today they released the documentation and samples. The sync services for ADO.NET enable you to develop occasionally connected clients much much easier. The sync framework provides easy detection of all the types of data concurrency and conflict handling issues you encounter when developing offline clients and makes it easy to code resolutions. Best of all it uses SQLce and the deploymemt package is under 2Meg. For more information see Steve's and Rafik's blogs.
BTW, I'll be speaking at DevTeach in May on the sync services and architectures of occasionally connected clients.