I recently needed service pack and edition information for a SQL Server 2005 installation on a server I was working on.  I figured I could get this information by simply using the Help --> About file menu option from within the Management Studio.  No luck, this didn't give me edition and version information.

I was able to get this information by using the SERVERPROPERTY Function.

SELECT  SERVERPROPERTY ('productlevel'), SERVERPROPERTY ('edition')

For a complete list of properties that this function can return see:  http://support.microsoft.com/kb/321185

For help using this function see: http://msdn2.microsoft.com/en-us/library/ms174396.aspx