It is highly relevant to overall network security. After 15 years as a heavy Internet user with zero virus, worm or spyware infections, I credit the Mac.
It is the WiFi access point that is the source of this vulnerability. You don't even have to have a computer on for this. Whether your ISP is Wireless, DSL, Cable, WiMax or whatever is also irrelevant. This is about your LAN, not your Internet connection.
Merely encrypting the wireless LAN will not prevent interception when the tower on the roof is blasting an unencrypted signal to the WISP. I use VPN and SSL tunneling past the WISP for stong encryption instead. Access control - not encryption - is useful for preventing unauthorized use of bandwidth.
Living in a rural area is relevant, though. :-)
Heh, network city-boys couldn't survive out here in the wilderness.
A point obfuscated by the thrust of the article, and most of the comments on this thread.