Unfortunately, no.
Bluetooth tethering in the iPhone OS is implemented as a one-way street: from the Internet connection already available on the iPhone, through Bluetooth to some other device.
There is no provision for tethering in the other direction - from an Internet connection on some other device, through Bluetooth, to the iPhone. Technologically, there is no reason why such a connection wouldn't be possible; it's just not something that Apple considered to be relevant as they were implementing the iPhone's Bluetooth software. Either they never thought of it, or they thought about it then discarded the idea for some reason.
In any event, no form of tethering in either direction was included in the version of the iPhone OS that runs on an iPod touch.
The first direction, from the iPod touch through Bluetooth to other device, would be useless because in order for the iPod touch to have Internet connectivity in the place, there would already be an active WiFi network in the area for the other device to connect to directly.
The second, from the other device through Bluetooth to the iPod touch, doesn't exist for the same reason that it doesn't exist in the iPhone.
All that said, I'm sure that there would be nothing stopping an interested and educated programmer from producing a jailbroken app that enables an incoming or outgoing IP-over-Bluetooth connection.