upload.php by default cannot. It can only have you upload one file at a time.
What about allowing you to upload an image specified by a URI ???
(Instead of a filename on your local PC?)
Honestly, the fastest way to upload more than one file at a time is by using an FTP program like Filezilla or SmartFTP or any of the other many free FTP programs out there. You can select and drag files over very quickly (too quickly – be careful) and easily monitor which ones are there compared to what’s on your hard drive.
If you want to manage images, the default WP method is pretty poor. You are better off using other methods to manage your images, and ftp as lorelle states to upload your images.
most of the image plugins SHOULD recognise ftped images once they are in their respective dir
What if your wordpress installation will feature multiple users posting images (multiple times) – but you do not wish to give these users access to your server via ftp?
It’s a bit late, but this thread needs a pointer to this great plugin for multiple file uploads:
http://wordpress.ex-libris.jp/inline-multiple-uploading/
