As for those people who run around with their cards in ad hoc mode,
especially here, they should know better.
One problem may be those "helpful" features where the OS is switching
to ad-hoc when there is no base station to be seen. In Mac OS X 10.2,
you can disable that (switch off "Allow this computer to create
networks" in Airport tab of Network pane), but you cannot disable
joining to an existing IBSS if the base station goes away. As the base
stations seem to go away a lot (an effect I don't understand yet), once
*somebody* starts an ad-hoc, the Macs will sooner or later find it and
then sustain it, as each IBSS Mac serves as a condensation point for
other Macs. Oops.
Fixed in 10.3, AFAIK. Unfortunately, not everyone is running that yet.
Now in Windows XP, it seems to have become positively hard to enable
Previous Windowses are a different story...