Tuxedup have written a small how-to to automount an USB storage media on Debian
Read the blog entry here
USB storage media are an ideal way to transfer files between computers without the need for a network or Floppy Disk. Not only can they hold a great volume of files, but now they are small enough to fit on your key ring. GNU/Linux is capable of using removable USB storage media and has been since the 2.4 release.
On a default install of Debian a user would have to manually mount the storage device from the command line, or write a script to do it for them. However this not ideal for new users, nor is it an ideal solution. What we want to do is have the computer automatically mount the USB storage media once it is inserted (In much the same way Microsoft Windows handles USB storage media).