Yeah, the first CTP of SQL
Server Everywhere Edition is ready to be "under test" (complete
with Books
Online) 
As explained by Steve
Lasker, this release has a couple of key features:
- Now supported on Windows XP, Windows 2003 and yes Vista
- |DataDirectory| macro for dynamic database location resolution
- Ability to GAC the ADO.net provider
- MSI for easily deploying SQL Ev w/ClickOnce, SMS and other deployment
technologies
- Visual Studio integration for ClickOnce
- Full support for all of the Sql Mobile features, including the
SqlCeResultSet and RDA.
This is one of the most interesting SQL Server edition I think so... happy
testing... 