Some adjustments to the PIE module from Jason's code review.

frameworks/compass/stylesheets/compass/css3/_pie.scss

@@ -11,6 +11,7 @@ $pie-base-class: false !default;
 //
 // * relative (default)
 // * z-index
+// * none
 $pie-default-approach: relative !default;
 
 // The location of your PIE behavior file
@@ -24,19 +25,26 @@ $pie-behavior: stylesheet-url("PIE.htc") !default;
 // or before the container's opaque background
 // should have a z-index set as well to ensure
 // propert z-index stacking.
-@mixin pie-container($z-index: 0) {
+//
+// The `$position` argument must be some non-static
+// value (absolute, relative, etc.)
+@mixin pie-container($z-index: 0, $position: relative) {
   z-index: $z-index;
+  position: $position;
 }
 
 // PIE elements must have this behavior attached to them.
 // IE is broken -- it doesn't think of behavior urls as
 // relative to the stylesheet. It considers them relative
 // to the webpage. As a result, you cannot reliably use
 // compass's relative_assets with PIE.
+// 
+// * `$approach` - one of: relative, z-index, or none
+// * `$z-index` - when using the z-index approach, this
+//                is the z-index that is applied.
 @mixin pie-element(
   $approach: $pie-default-approach,
-  $z-index: if($approach == z-index, 0),
-  $behavior : $pie-behavior 
+  $z-index: 0
 ) {
   behavior: $behavior;
   @if $approach == relative {

frameworks/compass/templates/pie/pie.scss

@@ -58,8 +58,9 @@ $pie-base-class: pie-element;
   @include pie-element(z-index);
 }
 
+// This is just a simple example of how to use the z-index approach.
 .widget {
-  @extend .pie-container; // This will
+  @extend .pie-container;
   h3 {
     @include pie(z-pie-element); // This will extend .z-pie-element instead of .pie-element
   }