You can run a Samba server on your Z and use smbmount on your Linux box to do what you want.
You can do that - I have tried it, but it's not very easy to get things working. Also, it seems a bit silly to have two Linux machines using a Windows protocol to communicate. If you've established a TCP/IP connection via USB, I think it's much easier to use sftp - in Nautilus, e.g., you can specify a folder as sftp://192.168.129.201 .
I have also had some problems with establishing the USB-TCP/IP connection, but as I have a small network and a netcard for my Zaurus, it is really much easier to just connect the Z to the network - then you can communicate with the Z as any other machine on the network.
/Jesper