Prerequisites
You need an iPod already formatted in Windows through iTunes, before you can proceed with this Howto. My iPod nano was already formatted with a Windows filesystem (fat32) as a factory default, but you may have one which uses the Mac filesystem.

Installing GTKPod
I'm using the program GTKPod for synchronizing my songs to the iPod. So first of all, you should install GTKPod.

If you want AAC support for GTKPod, type the following command in in the terminal:
sudo apt-get install gtkpod-aac
killall gnome-panel

without ACC support, the command would be: sudo apt-get install gtkpod
You can't have both installed at the same time.

Mounting the iPod
Now we're creating a mount point. You can skip this step, if Gnome created already one for you in the /media directory automatically.

First create the corresponding directory as a mount point for your iPod:
sudo mkdir /media/iPod

Let GEdit open the file fstab:
sudo gedit /etc/fstab

Add at the bottom:

/dev/sdc2 /media/iPod vfat nosuid,noauto,nodev,rw,umask=077,gid=1000,uid=1000,user,defaults,noatime,iocharset=utf8 0 0

Configuring GTKPod
When you go into GTKPod, go to Edit -> Preferences, Input/Output tab. I personally didn't get the auto mount/unmount thing working, so I left it unchecked.

However, the most important field in that entire preferences window is the iPod mount point field in the Input/Output tab. Fill in the mount point field with the appropriate folder (in this example /media/iPod).

Restart the program. It will automatically fill the GTKPod database with all of the songs and playlists that you have stored on your iPod prior to setting up GTKPod.

When problems occur
However, here is the rub: GTKPod seems to work randomly for different people. It will work on one synchronization, yet it will stop working for subsequent synchronizations. Others will find that it will not work, period. There's a simple solution to that, actually; just type the following command in into your console app:

sudo dosfsck -a /dev/sdc2

sdc2 being the partition where your iPod data resides. Be sure to check out /etc/mtab with gedit in order to confirm which /dev/ node is being used for your iPod.

The above command will execute dosfsck, and automatically fix any errors encountered in the vfat partition.

Have fun!
After that, GTKPod should work flawlessly without your system automatically mounting your iPod as read only. Now you can also write on your iPod and therefore synchronize your MP3 and AAC files.