SQL Server Compact Edition databases are supposed to a good idea for mobile phones and other portable devices;There's no service like SQLServer needed to run against them, it's kind of like an access database in that regard.

I think the target audience is actually Laptops that need to sync with a master database on an intermittent basis, because you can make push/pull replication subscriptions to them. You know, the typical, in the field issues where they need access to database stuff, add invoices, and sync later.

At least for smaller devices/ mobile development, The problem is that it requires the compact .NET framework, which in turn requires the Windows mobile operating system.

Since that's not as popular as say, the Android OS, your future markets a little more limited; I ended up using SQLite database instead, as there's more code examples for using that, and can be used with or without the Windows OS on those portables, as well as in full windows Operating systems.