I'm thinking about moving back to Ubuntu from Windows but the one thing I
must have is support for my iPod nano 3G - is there an itunes like piece of
software that support the newer iPod for Linux without having to change
anything on the iPod iteself?

You will have to add a checksum to the ipod to use it with any libgpod
using app. It's trivial, and doesn't cause issues with iTunes in my
experience.

I have a RCA I-Pod and ALL the support software is written for Windows.

Why would anyone ever buy anything when "ALL the support software is written
for Windows"? Have we learned nothing at all since '98? I don't know about
the iPod but Linux tools supports my Palm LifeDrive's pTunes just fine hence
my use of the Palm Lifedrive!! I own a few thousand AT&T shares too, but
I'll NOT be forced to own an iPhone because I am not free to use the phone
provider I may choose. Proprietary shackles are the very thing we are trying
to avoid! IF manufactures will not provide the info to our Linux developers,
we are better off learning that early and avoiding their merchandise aren't
we?