These days you never know where the next hacking attempt on your wireless network may come from. In this case, it's from the police, as authorities start mimicking wardriving behavior :
"The Douglas Country Sheriff's DOffice says it's going to start warning computer users that their networks may be vulnerable to hackers. The Sheriff's Department plans to equip several of its community service and patrol cars with devices that detect unprotected computer networks. In cases where investigators can figure out who owns the networks, they'll try to warn of potential security issues. They'll also drop off brochures with instructions to computer users on how to password protect their networks."
Back in 2004, Kelly Martin wrote a very pragmatic article on Catching a virus writer, empasizing on how "with the consumer WiFi explosion, launching a virus into the wild has never been easier and more anonymous than it is today." Moreover, Kaspersky labs recently assessed the situation in England, and you can easily see the need of basic awareness there.
I don't feel it's a good idea mainly because it generates more noise for the end user to sort through. They'd rather assess and position on a map the regions with most vulnerable networks and figure out a cost-effective ways of spreading awareness in these regions, instead of taking the role of an ethical wardriving. On the other hand, if they start taking care of wireless, would they start taking into consideration Bluetooth as well? There're just too many ethical wardrivers to deal with and deceive these days, and creative end users tend to multiply themselves or, of course, use common sense protection.
WarDriving Awareness brochure courtesy of Tom Hayward. Recommended reading - "War, Peace, or Stalemate: Wargames, Wardialing, Wardriving, and the Emerging Market for Hacker Ethics".