Yes, your network is safe from people using NetStumbler. But people with Linux can get wlantools, which includes a handy tool called wlanwatch.

http://www.sublimation.org/security/localarchive/802.11/

It shows all frames coming from your AP. And your ESSID is *not* hidden there.

The only problem is that wlantools does *not* scan all channels, so i had to write a little script that cycles through them.

i need to figure out how to get the channel, timestamp, and maybe even GPS info into the log, and to eliminate some of the extra stuff that i don't need.

(wlanwatch actually dumps out a *lot* of info, as it puts your wireless card into "promiscuous" mode, where it listens to everything.)

BTW, it doesn't work with the Lucent/Orinoco/Agere Wavelan cards. It works with cards that use the Prism2 chipset, like the Linksys, SMC, D-Link, Compaq, and more.