To use this, you need a copy of iLife '11 installed and Photo Stream turned on in iCloud (Settings > iCloud). You also need to do a little scripting yourself. Open Apple Script Editor (Applications > Utilities) and paste in the following code:
tell application "Finder" set this_folder to "Macintosh HD:Users:user:Library:Application Support:iLifeAssetManagement:assets" as alias set target_folder to "Macintosh HD:Users:user:Pictures:MyStream" as alias try duplicate (every file of the entire contents of this_folder whose name contains "IMG") to the target_folder with replacing end try end tell
Before you're finished, you have to replace the target path folder (Macintosh HD:Users:user:Pictures:MyStream) to the folder of your choosing on your hard drive.
Click run in Automator and it should copy all your Photo Stream files over to the MyStream folder inside your Pictures folder. You can edit the location to anywhere you like by changing the "Macintosh HD" line. It's not a bad replacement if you're looking to skip the iPhoto step to get your photos from your Photo Stream to a folder. Find more information, help, and a couple other ways to do the same thing over at Macworld.
10.7 Auto-copy Photo Stream images to a folder | Mac OS X Hints