<p>How do I write the SQL code to INSERT (or UPDATE) an array of values (with probably an attendant array of fieldnames, or with a matrix with them both) without simple iteration?</p>

I construct the list as an xml string and pass it to the stored procs. In SQL 2005, it has enhanced xml functionalities to parse the xml and do a bulk insert.
check this post:
Passing lists to SQL Server 2005 with XML Parameters