KB article discussing how to change the service account passwords in MOSS 2007 and WSS 3.0 has been released
INTRODUCTION This article describes how to change the password of service accounts in Microsoft Office SharePoint Server 2007 and in Microsoft Windows SharePoint Services 3.0. Use the procedure in the “More Information” section to update the password if the password of service accounts expires. https://support.microsoft.com/default.aspx?scid=kb;EN-US;934838