Is there a way to upload multiple images all at the same time in Drupal 7?
See the Plupload integration module. From the project page:
Provides integration between for the Plupload widget to upload multiple files and Drupal. Plupload is a GPL licensed multiple file uploading tool that can present widgets in Flash, Gears, HTML 5, Silverlight, BrowserPlus, and HTML4 depending on the capabilities of the client computer.
You can use the Plup module.
This module integrates a modern Plupload library with file field in Drupal 7. It provides a field widget for image field that allow user to upload multiple images at once using Plupload library. It depends on Libraries module.