Flash with php?, Javascript?, java?, asp?, cfm?, other?

[bluewalrus]

Does anyone know how the gmail uploader works? I'm wondering about the multiple files upload. I noticed the "Attach a File" link is Flash. When it opens instead of having the option of "open" for which file you want to attach it has "select". You can also use ctrl or shift to select multiple files at this instances. I found these other 2 sites that also use the same or similar (since I don't know how google does it either) technique.
http://www.yourfilehost.com/flash_upload.php
http://www.mediafire.com/

I don't believe flash is capable of this by itself so I'm wondering if anyone has any ideas how this is achieved? Thanks.

[bluewalrus]

Found it, don't know how it works yet though.

http://demo.webdeveloperplus.com/jquery-swfupload/