This feature is available in the Jay Cooke (8.05) release of Deki Wiki.
Uploading files through the default browser mechanism poses two problems: a horrible user experience when uploading multiple files, and no visual feedback as to the progress of an upload. Through the addition of the Flash-based MIT-licensed SWFUpload, we can improve the file uploading experience inside Deki Wiki.
Additionally, Deki Wiki never allowed the uploading of files while the editor was open, since file attachment required a page reload. This use case is improved, as we now do all file uploading through an asynchronous operation.
The flash uploader is enabled by default starting with the Deki Wiki 8.5 release. If you do not find the functionality desirable in your Deki Wiki, you can turn the flash uploader off (and revert to the old uploader) by adding to LocalSettings.php:
$wgFlashUploader = false;
Clicking "Attach file or image" auto-launches the new uploader. Note that the uploader will launch your dialog by default:

Multiple items can be SHIFT-selected or CTRL-selected:

Upload selection of files, you can see the list of files that will be uploaded; additional files can be added by clicking the "Add more files" button:

Selecting a single item will allow you to set the file description, as well as get metadata about the file:

Uploading the file shows a progress bar of each file as it uploads:

| File | Size | Date | Attached by | |||
|---|---|---|---|---|---|---|
| flash uploader.swf No description | 3.13 MB | 23:23, 15 Apr 2008 | RoyK | Actions | ||
I'm thinking I will just need a large message when a user uploads a file above the max size linking them to a simple tutorial on how to use Picasa or another program to scale down their images.
I did update the player, to no avail...I am very sad :-(