Check this out:
According to the Dark Sun fan site The Burnt World of Athas, Baldman Games (which runs games at cons) has received permission from Wizards of the Coast to distribute Baldman's Dark Sun convention games (designed for 4th edition) to non-con attendees.
The catch? Baldman can't post them online for free download. And neither can you, if you get them in your grubby little hands.
You have to pony up an email address first, and then you'll receive the files via email over several days -- seven zip archives in all, plus links to a Dropbox account holding maps and pregens. They're yours for FREE, but you have to agree to keep them off the open web, filesharing services, the *chanz, and all the "ahoy there matey" sites.
Check out the details here, or this forum post at Baldman Games.
Just for the sake of info, the zip files are rather large, so if your email storage quota is tight, be forwarned (somewhere in the 8-to-20 megabyte range). I don't think this is too much of an issue for most folks, but if you are on a pokey 'net connection (like me), then you'd might like to know.
I don't play 4e, but I love to snag stuff for inspiration and adaptation. Since these are free, you might as well request them.