Just looking at page 15 of Ulmer's applied grammatology again, trying to puzzle through the distinctions that Ulmer is making between Derrida and McLuhan, or actually, Heidegger and McLuhan, because Ulmer is saying that Derrida turns to Heidegger rather than McLuhan to work out grammatology, the study of writing. Ulmer says Derrida does this because McLUhan "projected the return of an oral civilization" while "Heidegger located the essence of modern technology in the family of terms related to Gestell (enframing). . . . Derrida took up the question of enframing, as indicated in his exploration of all marginal and paragonal phenomena, in order to prepare the way for the shift away from, or the deemphasis of, speech in favor of writing" (15).
Okay--big breakthrough in understanding here, maybe. While not versed in Heidegger and the subtleties of enframing, it seems to me that McLuhan's "the medium is the massage" is very much a mantra for paying attention to enframing. It also seems to me that McLuhan (and Ong) did not so much project a return to oral civilization as simply notice, and in some ways document, the return of orality, a pattern that is increasingly clear especially when images are understood as "acoustic" in their orientation, or perhaps more precisely, if images are understood to be closer to speech and orality than they are to writing and inscribing. The flip side of this argument would be simply to say that it is increasingly clear to me that we are not culturally making a shift towards writing.
That said, I believe there are probably some Derridian nuances to tease out of "writing" and the shift Ulmer says Derrida favored. Later on the page, Ulmer does write "before grammatology can attain its applied status by working in the video medium, whose audiovisual capacity seems to fulfill the requirements of a double-valued writing (phonetic and ideographic . . . ), certain theoretical problems must be resolved" (15). This "double-valued" writing--phonetic (oral) and ideographic (image? inscription) might actually be a another way of saying that Derrida, like McLuhan, was actually trying to work on the problem of "interfacing" as much or more than "enframing."
My new working title. McLuhan for Compositionists: Working at the Interface.