Interpolation and foreach

gistfile1.sass

// Sass
$selectors: {foo, bar, baz};
foreach $selectors as $selector {
  .#{$selector} { background-image: url("../images/#{$selector}/background.png"); }
}

// CSS
.foo {
  background-image: url("../images/foo/background.png");
}
.bar {
  background-image: url("../images/bar/background.png");
}
.baz {
  background-image: url("../images/baz/background.png");
}

This is supported in Sass 3.1. The syntax is:

$selectors: foo, bar, baz;
@each $selector in $selectors {
  .#{$selector} { background-image: url("../images/#{$selector}/background.png");
}