Well there is a painstaking way to do it, if u have the time and the patience.
Plug in your nano, go to my computer and click on the ipod drive. Make sure that all hidden files are visible.
In the drive there will be a folder called Ipod control, in there are all your songs, but they are written in 4 letter codes. You can straight copy those files and save them anywhere on your computer. Those files can be played on itunes, or WMP, whatever.
Now u gotta listen through the songs and re-name them all. Takes forever lol.
Then put the songs u want into your itunes and plug your ipod touch.
Thats the only way i found I could go between ipods.
Hope it helps,
good luck