USB device permissions

[Peter Clark]

    Currently, if I plug in a USB mass-storage device (let's say a card 
reader) and then mount it (by clicking on the icon that appears on the 
desktop), the permissions are drwx------ mla mla /media/sda1. 
    What needs to be modified in order to allow anyone in groups "users" to 
also read/write to the device? E.g., drwxrwx--- mla users /media/sda1. I was 
looking at the scripts in /etc/udev, /etc/hotplug (and hotplug.d), /etc/hal, 
but I'm not seeing where the permissions are set. Maybe I just overlooked 
something?
    Thanks,
    :Peter