Bart Desmet has posted a cool article: Getting started with SQL Server 2005 Everywhere Edition. I think this is a cool technology, that can be used a lot easier than SQL Server Express. It's smaller, needs less memory, doesn't have to be installed as a service, and can run in-process. A cool usage for this would be to use SQL/e as a file format for your application. If you're creating a word processor, or any document-oriented application, you could use SQL/e instead of creating a custom file format.