Does anyone have a script to duplicate multiple pages in CS4?

This is a very basic script, just written for you on CS3 and totally untested:

if (app.documents.length == 0){
    alert ("Please open a document, select an object, and try again.");
    exit();
}

var myDoc = app.activeDocument;
var myPage = myDoc.layoutWindows[0].activePage;
var myPageId = myPage.id;
var myDialog = app.dialogs.add({name:"Duplicate pages"});

with(myDialog.dialogColumns.add()){
    with(borderPanels.add()){
        staticTexts.add({staticLabel:"Duplicate front-most page # " + myPage.name});
        var myIntBox = integerEditboxes.add({editValue:1, smallNudge:1, largeNudge:10});
        staticTexts.add({staticLabel:" times"});
    }
}

var myResult = myDialog.show();

if(myResult == true){
    var myNumber = myIntBox.editValue;
    if (myNumber < 1) {
        alert(myNumber + " is invalid number.");
        exit();
    }

    for (i = 0; i < myNumber; i++) {
        myPage.duplicate(LocationOptions.AFTER, myDoc.pages.itemByID(myPageId));
    }
}

myDialog.destroy();

It duplicates the active (the front-most page) — its number you see in the bottom left corner of the document window. You can type a number or use up/down arrows to increment it by 1 (add shift key to increment it by 10).

Hope it helps.

Kasyan