SharePoint SDK has been updated as expected to bring it up to date with the recent SharePoint SPS and WSS Server Pack 2 releases.
Download link to the updated SDK and excerpt:
The Service Pack 2 (SP2) release of Microsoft Office SharePoint Portal Server 2003 adds a supported API that you can use to update SharePoint Portal Server 2003 with changes to user accounts. When a user is migrated in the Active Directory directory service, the security identifier (SID) changes for that user. Additionally, the logon information for that user might be changed. Microsoft Windows SharePoint Services 2.0 and SharePoint Portal Server 2003 store user information based on both the user's SID and the user's logon information. When the user's SID or logon information changes in Active Directory, Windows SharePoint Services 2.0 and SharePoint Portal Server 2003 must be updated with the new user information before that user can successfully access SharePoint Portal Server 2003. Using the new, supported account migration APIs, you can update SharePoint Portal Server 2003 with new user information.