Since version 6 of Windows Mobile, every version of Windows Mobile (6, 6.1, 6.1.4, 6.5 and 6.5.3) have included SQL Server Compact Edition version 3.1. But each OS version has contained a newer build of 3.1. The desktop RTM version of SQL Compact was 3.0.5300.0.
The table below summarizes the various OS version and the corresponding SQL Compact build number:
|Windows Mobile version||SQL Compact build|
Look here for a list of hotfixes and corresponding build numbers.