They used LaTeX[1].. look at the source files:
http://clojure.googlegroups.com/web/clojure-cheat-sheet.zip
-Ben
1.http://www.latex-project.org/
In case you were interested in the HTML version, you can find the HTML
and CSS without the Clojure website stuff here:
http://raek.se/clojure-cheat-sheet.html
As for tools, all I used when I reformatted the cheat sheet to HTML
was a text editor, but I don't think it's too difficult to write a
program that generates this sort of cheat sheets -- both in HTML and
LaTeX.
If you're choosing from LaTeX and HTML, I recommend going for LaTeX,
since HTML's layout capabilities are really primitive and you have to
use some ugly trick to get things the way you want. However, HTML has
the advantage that you don't need any additional software.
-- raek