I found this post searching for exactly those 2 classes :D

I manage to make it work together, but I found a problem with class.upload: doesn’t work with remote files, so my solution was:
1. upload the img
2. resize and put the thumb in a folder in my server using Class.Upload.PHP
3. move the thumb to amazon using Amazon S3 PHP Class
4 delete the thumb in my server.

Have you found a better way? Could be possible resize on the fly and put the thumb directly in amazon with the Amazon S3 PHP Class?

Thanks!