http://www.adobe.com/support/downloads/detail.jsp?ftpID=1536

very recomandable

here is an example exporting Layers into Gifs:
(like you would need it, if you capture a lot of screenshots into layers)

// loop through the document and set each layer's visibility to false
for(var i=0; i<activeDocument.layers.length; i++) {
     // if it's a layer set, loop through it too
     if(activeDocument.layers[i].layers) {
          for(var j=0; j<activeDocument.layers[i].artLayers.length; j++) {
               activeDocument.layers[i].artLayers[j].visible = 0;
               }
          }
     // otherwise just set its visibility
     else {
          activeDocument.layers[i].visible = 0;
          }
     }

// loop through the document and set each layer's visibility to visible
// save it as a gif
// set its visibility back to false
for(var i=0; i<activeDocument.layers.length; i++) {
     activeDocument.layers[i].visible = 1;
     
     // it's not a layer set
     if(!activeDocument.layers[i].layers) {

          // set its name to layer name in a directory called "temp"
          // in the same location as the script

          gifFile = new File( "temp/"+activeDocument.layers[i].name+".gif" );
          gifSaveOptions = new GIFSaveOptions();
          gifSaveOptions.colors = 256;
          gifSaveOptions.dither = Dither.NONE;
          gifSaveOptions.matte = MatteType.NONE;
          gifSaveOptions.preserveExactColors = 0;
          gifSaveOptions.transparency = 1;

          activeDocument.saveAs(gifFile, gifSaveOptions, true, Extension.LOWERCASE);
          activeDocument.layers[i].visible = 0;
          }
     // it is a layer set
     else {
          // loop through the set
          for(var j=0; j<activeDocument.layers[i].artLayers.length; j++) {

               activeDocument.layers[i].artLayers[j].visible = 1;

               // set its name to layer name in a directory called "temp"
               // in the same location as the script
               gifFile = new File( "temp/"+activeDocument.layers[i].artLayers[j].name+".gif" );
               gifSaveOptions = new GIFSaveOptions();
               gifSaveOptions.colors = 256;
               gifSaveOptions.dither = Dither.NONE;
               gifSaveOptions.matte = MatteType.NONE;
               gifSaveOptions.preserveExactColors = 0;
               gifSaveOptions.transparency = 1;

               activeDocument.saveAs(gifFile, gifSaveOptions, true, Extension.LOWERCASE);
               activeDocument.layers[i].artLayers[j].visible = 0;
               }

          activeDocument.layers[i].visible = 0;
          }
     }

[via lucanboots@]