I can understand there not being any highlighting by default, but it's difficult to demonstrate problems with the highlighting here (besides this one, obviously) when you can't even do it by specific request.
For example, this source:
<!-- language: lang-c -->
#include <stdio.h>
main(int argc, char *argv[])
{
printf("Hello, World!\n");
}
currently produces this rendering:
#include <stdio.h>
main(int argc, char *argv[])
{
printf("Hello, World!\n");
}
which is utterly lacking in color, and does not bear the "lang-c" class.