A Google Script for emailing Google Drive folder-updates to a group of recipients.

gscript_folder_notifier.gscript

// Copyright 2016 Wojciech Dziemianczyk
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

function notify() {
  
  // statics
  var folderName = 'kittens';
  var dataStorefileName = 'last_updated_kittens_store';
  var emails = ['firstEmail123@example.com', 'otherEmail124@example.com'];
  
  // Check for store file, get the last updated time
  var currentTime = new Date().getTime();
  var lastCheckedDate = new Date(0);
  var storeFiles = DriveApp.getFilesByName(dataStorefileName);
  
  if (storeFiles.hasNext()){
    var storeFile = storeFiles.next();
    var content = Number(storeFile.getBlob().getDataAsString());
    lastCheckedDate = new Date(content);
    storeFile.setContent(currentTime);
  } else {
    DriveApp.createFile(dataStorefolderName, currentTime);
    return;
  }
  
  // Check for new files
  var emailBody = 'New files have been added to ' + folderName + '. Files added: \n\n';
  var folder = DriveApp.getFoldersByName(folderName);
  while (folder.hasNext()) {
    var kittensFolder = folder.next();
    var files = kittensFolder.getFiles();
    var updatedFilesFormatted = '';
    
    // If there are files in the folder
    if (files.hasNext()){
       while (files.hasNext()){
         var file = files.next();
         // And if the lastUpdated date is greater than the lastCheckedDate
         if (file.getLastUpdated() >= lastCheckedDate){
           // Format & appened to a String
           updatedFilesFormatted = updatedFilesFormatted.concat(file.getName() + '\n');
         }
       }
      
      // If our formatted string is not empty, email the list to emails
      if (updatedFilesFormatted.length > 0){
        for (var i = 0; i < emails.length; i++){
          GmailApp.sendEmail(emails[i], folderName + ' was updated', emailBody.concat(updatedFilesFormatted));
        }
      }
    }
      
    break;
  }
}