Get id/username of the uploader

i’m also interested.

I too wanted that information. I also wanted to know which gallery was modified. Seeing that the plugin seems to have no one maintaining it, I gamble that any changes I make to it won’t be updated and overwritten anytime soon.

Use the following at your own risk. Find and edit the following file:
plugins\nextgen-public-uploader\inc\npu-upload.php

Near the bottom of the file, find the email notification function and replace it with this:

// Function: Send Email Notice
		public function sendEmail() {
			global $wpdb;
			global $current_user;
			get_currentuserinfo();
			$gal_id = $_POST['galleryselect'];
			if(get_option('npu_notification_email')){
				$to = get_option('npu_notification_email');
				$subject = "New Image Pending Review - NextGEN Public Uploader";
				$message = "A new image has been submitted and is waiting to be reviewed.\r\n";
				$message .="Uploaded by $current_user->user_login, $current_user->display_name, $current_user->user_email.\r\n";
				$message .="To gallery: $gal_id \r\n";
				wp_mail( $to, $subject, $message);
			}
		}

This code adds 2 new lines to the message. The first provides Username, Display Name, and email address of the user making the upload. The second provides the ID number of the gallery.

Perhaps, if someone actually picks up responsibility for the plugin they can add something similar.