Ok, here's the solution which works:
// Storing the file name in the queue
var fileName = "";
// On file add assigning the name of that file to the variable to pass to the web service
$('#fileupload').bind('fileuploadadd', function (e, data) {
$.each(data.files, function (index, file) {
fileName = file.name;
});
});
// On file upload submit - assigning the file name value to the form data
$('#fileupload').bind('fileuploadsubmit', function (e, data) {
data.formData = {"file" : fileName};
});