MARSHALL MCLUHAN, what are you doin'? During the late '60s, that glib one-liner became a running gag on Laugh-In, network television's kooky answer to the counterculture. It confirmed that McLuhan, a Toronto academic, had become an unlikely icon of American pop culture, a household name like Timothy Leary or Chairman Mao. But it was also a sign that this communications guru, the most prodigous intellectual of his time, was becoming absorbed, and erased, by the very phenomenon that he analyzed with such acuity -- loss of identity in the media vortex. THE MEDIA had their fun with McLuhan, treating him as a perplexing novelty act. And now there are university graduates who draw a blank when you mention McLuhan's name. There's no mention of McLuhan in Naomi Klein's 'No Logo,' the best-selling bible of the anti-globalization movement. Finally, however, McLuhan appears to be enjoying a comeback. Last week, at Toronto's Tarragon Theatre, award-winning Canadian playwright Jason Sherman presented a public workshop of 'The Message,' a new play about McLuhan struggling to recover his memory after a stroke.Directed by Kevin McMahon, McLuhan's Wake, a feature co-produced by the National Film Board, examines its subject in McLuhanesque style, choreographing his ideas with a maelstrom of images, or "world pool".