The Winter issue of Critique: Studies in Contemporary Fiction
(Table of Contents
) contains essays about fiction writers who have died over the past decade.
It includes an essay David Foster Wallace: “That Distinctive Singular Stamp of Himself” by his Illinois State University colleague of 10 years, Charles B. Harris. It is an insightful piece about DFW, includes a number of moving personal anecdotes and considers his wide reaching achievements.
It's not yet available freely online (I'm not sure if it will be) but if you have access to academic journals through your work you should be able to track it down.