"Ubuntu’s NetworkManager 0.7.0 contains the necessary
features for creating an Ubuntu adhoc network host.
"In Ubuntu:
Left click on the NetworkManager icon and select Create New
Wireless Network
"Specify an adhoc network name, i.e. UbuntuAdhoc
Select your favorite security method (this example specifies
None)
Click the Create button
"As of Ubuntu 8.10, NetworkManager pretends to connect to the
newly created UbuntuAdhoc wireless network but inevitably fails and
the NetworkManager defaults back to the last successful network
connection. See below to rectify"