Linux doesn't have any drivers to install, assuming you're running a v2.6 kernel. These instructions assume you're running Ubuntu. Each linux distribution is different, but the instructions should be basic enough to follow for other distros.
You can verify your kernel version by running uname -a in a terminal window, note that this kernel is version 2.6.20
Sometimes the Linux distribution installs brltty (braille device) which will conflict with the Arduino. You must uninstall brltty! Do so by running
sudo apt-get remove brltty
In a terminal window. If it says it's not installed then thats OK. If you're not running a Debian-derived installation use whatever tool is necessary to verify that you don't have brltty running
Plug in the Arduino, verify that the green LED is lit, and type ls /dev/ttyUSB* into a terminal window, you should see a device file called something like ttyUSB0
Depending on your Linux distro, it may be /dev/tty/USB0 or /dev/tty.USB etc.
If you can't seem to find it, use dmesg | tail right after plugging in the Arduino and look for hints on where it may put the device file. For example here is says Serial Device converter now attached to ttyUSB0
If you see something like this
[ 1900.712000] ftdi_sio 2-10:1.0: FTDI USB Serial Device converter detected [ 1900.712000] drivers/usb/serial/ftdi_sio.c: Detected FT232BM [ 1900.712000] usb 2-10: FTDI USB Serial Device converter now attached to ttyUSB0 [ 1901.868000] usb 2-10: usbfs: interface 0 claimed by ftdi_sio while 'brltty' sets config #1 [ 1901.872000] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0 [ 1901.872000] ftdi_sio 2-10:1.0: device disconnected
That means you have not uninstalled brltty and you should try again.