I've just installed the latest version of plupload to my local test PHP server, running the HTML5 uploader. Everything seemingly works ok however I cannot determine where the files are being uploaded to (and how to change this to a directory that I would like to set).
Here is the file - http://jsfiddle.net/SQ9aB/
The url is in the property "url" of your configuration object.
$("#html5_uploader").pluploadQueue({
// General settings
runtimes : 'html5',
url : 'upload.php',
max_file_size : '10mb',
chunk_size : '1mb',
unique_names : true,
....
in this case to upload.php