Just downloaded SP1 for SQL 2008 and tried installing it on my development workstation. This workstation only has the tools/SDK/SQL Books installed.
When I get to the 'Select Features' screen it won't let me proceed. The description for the shared features is: The version of SQL Server instance Shared Component does not match the version expected by the SQL Server update. The installed SQL Server product version is 10.0.1300.13, and the expected SQL Server version is 10.0.1600.22.
The error when trying to proceed is: [Error Message] There are no SQL Server instances or shared features that can be updated on this computer.
I also posted this on Technet (http://social.technet.microsoft.com/Forums/en-US/sqlsetupandupgrade/thread/8ef8f163-0adf-4d71-8ddd-3c1d566fd77f) and got some responses including one indicating that I had the February CTP version installed. When I checked the 'about' box in SSMS it gave the following results:
Microsoft SQL Server Management Studio 10.0.1600.22 ((SQL_PreRelease).080709-1414 )
Microsoft Analysis Services Client Tools 2007.0100.1600.022 ((SQL_PreRelease).080709-1414 )
This did indicate a pre-release - yet I knew that I installed from the Developer Edition DVD I purchased. I uninstalled/reinstalled SQL 2008 from the same media (Setup.exe timestamped 07/10/2008) and even after that it still had the same issue.
I also checked my home system which was installed from the Technet Plus Enterprise Edition. Both the tools installed on my workstation and the Virtual TestBed Server I setup have the same issue. The server version is reporting correctly (10.0.1600).
There is no commonality I can find. I've found this issue on XP SP3, Vista, and Windows 2003 Server, x86 and x64.