The SQL Server 2008 Express Service Pack 1 has been released. The internal workings and layout of this package are different than what we had in SQL Server 2005 Express, but the same level of functionality is offered. This package uses the slipstream functionality as I discussed here but optimized for the Express experience.
This package can:
By default, when you run the package it defaults to scenarios described in #1. If you would like to update (scenario #2) you need to specify /Action=Patch on the command line and then everything else is the same.
The full Service Pack can also update Express original release to Express SP1.
Starting with SQL Server 2008, we won’t be shipping new packages of "Express with Advanced Services" or "Express with Tools" with Service Pack 1. To update these editions, you will need to run the full Service Pack 1. The SQL Server 2008 Service Pack 1 (SP1) is now available on Microsoft Update as up April 28th. See the annoucement here
The SQL Server 2008 Management Studio Express package can be upgraded to Service Pack 1 by apply the SQL Server 2008 SP1 through Microsoft Update.