Hi,
I have a Nokia N8 as well and looked in vain for something like tethering on the phone itself. My Sony Android had such a feature. I looked for mobile hotspot...nothing.
Now I know I had to look for a way to create an new obile broadband connection on the PC.
I know the way to do it in Linux Voyager X2 (combi Ubuntu-Debian).
Itś very easy.
Just plug the N8 in via USB cable.
Evt. you have to unlock your phone. I did, before Linux / Windows actually recognises the phone.
Than, you go to Network Manager of search for Network Connections.
Choose Add / New Mobile Broadband
Choose provider and Create and that´s it.
Evt. you have to Enable Mobile Broadband ( in my case T-Mobile)
Otherwise you can pick your newly created mobile broadband from the dropdown menu.
Happy surfing, Peer