Tethering the eDGe seems like it's just out of reach:

1. WiFi buddy app sees ad hoc networks but can't (yet) connect.
2. Entourage staff has said that the eDGe can theoretically be tethered to, but haven't said if any particular device works or how it can be made to work.

Of the three ways to do tethering (usb, bluetooth and ad-hoc network) none currently work, as far as I know. Only devices that create a genuine Wifi signal out of a cell signal - e.g. mifi, router + usb broadband modem, and HTC Evo apparently, can be "tethered" to the eDGe.
If anyone has gotten any further with this, please post!