Thayer School now has an official logo guide, complete with examples of unacceptable variations of the logo.

The guide seems fairly down-to-earth, unlike some of the highly technical standards found elsewhere. Dartmouth itself does not seem to have taken this step yet.

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[Update 12.14.2013: The Geisel School seems to have been first: its guidelines (pdf), much more rigorous, were published in April of 2012. See this post.]