To test the Drag Drop Upload recipe, while editing the page, drag one or more files from your file manager and drop them in the page. They will be uploaded asynchronously, without you leaving the page.
The files will be listed above the edit form. To insert a filename in the wikitext area, click on it -- it works like the buttons of the edit toolbar.
The script currently works only with Firefox 4+, Chromium, Google Chrome and Safari.