I've just completed composing a scholarly book using LaTeX and it has been accepted for publication. Are there legal requirements for 1) acknowledgments or 2) permissions connected with the use of LaTeX in a published book? I don't see anything about the latter in the current versions of the docs for the packages I've used.
Edit: Frank Mittelbach has pointed me to a paper he has recently published on the history of the LaTeX Project Public License: TUGboat 32(2011)/1:83–94. Section 1.2 (p. 84) contains a digression on the multicol license and its current status. He describes the multicol "moral obligation" license as "perhaps the most curious license ever drawn up."
multicol. More broadly, the question does not limit us to packages in TL/MiKTeX. – Joseph Wright♦ Mar 2 '12 at 19:43