Ahead of the final release in December 2006, Microsoft have

released SQL Server Compact Edition RC1

SQL Server 2005 Compact Edition is a very lightweight, in process relational
database engine for use in desktop applications and mobile devices. It has an
extremely small footprint (~3MB) and minimal overhead. It won’t use any where
near as much memory as Express so its suitable for memory pressured systems. It
works on Windows 2000 SP4, Windows Server 2003 SP1, and Windows XP SP2.

The main

SQL Server Compact
page has yet to be fully rebranded. The SQL Server
Compact Edition RC1

readme is available
, as are

RC1 Books Online

I first heard about this on

Steve Lasker’s blog
. There’s more on the

SQL Server Everywhere Blog