When you say a "wireless dongle", presumably this is Mobile Broadband via the cellphone network and not a USB Wireless Network Adapter connecting to a router?
If this is the case, and the Netbook has built-in WiFi that isn't being used, then theoretically its internet connection could be "shared" with an iPod, provided the iPod supports connecting in an Ad Hoc network. This is a wireless network in which two computers connect directly rather than via a router (Infrastructure network). To be honest, I wouldn't relish the prospect of trying to get that to work, if it is actually possible.
As an alternative, the "Three" mobile network has what they call MiFi, which is actually a wireless router that connects via the mobile network. This could be used with both Netbook and iPod.
This is the Orange Mobile WiFi device which is similar. I'm not aware of the other networks having an equivalent device, they only have USB dongles.