So I tried this:
<% require combine_files("style.css", array(
"$themeDir/css/reset.css",
"$themeDir/css/lightbox.css",
"$themeDir/css/fonts.css",
"$themeDir/css/form.css"
)) %>
Doesn't work. It spews out a warning:
[Warning] Invalid argument supplied for foreach()
And of course doesn't include the files. Turns out the array is passed as a a string, e.g. "array". Literally.