I just bought a new Sony VAIO SRX-77P that includes the built-in 802.11b Wi-Fi link. There's a switch on the side of the unit to disable the wireless link when not needed. Whilst aboard a plane would be an obvious reason to turn it off, so would being in a non Wi-Fi environment using the battery. I would imagine most units would include an on-off switch simply for power management purposes.

[This message has been edited by Sierra Kilo (edited 05-27-2002).]