The SD drop, called Project Space Planes, will drop the paper airplanes from a weather balloon 21 miles above the Earth (the paper is waterproof). We don't know the drop location, but they'll likely travel pretty far.
Each memory card will contain pictures, videos, or music that, if found, can be uploaded to the Project Space Planes website. The recipients of the falling memory cards will be able to keep the SD card, and contact the person who made the original message.
Samsung is promoting their new line of magnet-proof, waterproof, X-ray proof, and shock proof SD cards. These 'Plus' SD cards also double your transfer speed. Check out the video below, and visit Project Space Planes to upload your own message.
source: Samsung (Project Space Planes) via CNET