If you're developing Line-of-Business (LOB) applications that have needs beyond the cool stuff provided by SQL Everywhere, then you'll definitely want to take note of the recent work in MS patterns & practices:

The Microsoft patterns & practices team has released the first Community Technical Preview (CTP) for the Mobile Client Software Factory.  The factory will help architects and developers design and build mobile LOB solutions.   The Mobile Client Software Factory will include a prescriptive architecture, application blocks, and other guidance/tools for enterprise architects and developers targeting Windows Mobile powered devices.  If you’re serious about building mobile enterprise solutions, join the community, download the latest pre-release drop, and start contributing feedback today!

There's some really good stuff in there around local caching and ensuring continuity of functionality during offline/intermittent connection.

Oh, and if SQL Everywhere is new to you (or for more information), check out a great post by Steve Lasker, a PM over on that team.