On my father's MBP late 2009 upgraded to Lion it doesn't work. You give the "create network" command and nothing happens, the AirPort stays connected to the original wlan it was connected to.
I don't need to share a connection, i just need this to be able to use the Remote App on my iPod for controlling iTunes at my sister's wedding tomorrow.
I also tried to create a new user-account thinking that this machine is too messy, but no luck.