Pay Credence to Credant's Claims on Sleeping Wi-Fi?

Credant, a UK firm that sells data encryption tools, claims thieves sniff Wi-Fi in laptops stored in cars: I've been letting this percolate for a couple of days in my head, and would appreciate comments from those of you who know the nitty-gritty. Credant is claiming that thieves can use Wi-Fi detectors to find laptops in cars that have Wi-Fi active, because some laptops don't go to sleep for 30 minutes after the lid is closed or sleep is activated. (Thus, Credant says you need to have encryption software installed to prevent access to data, rather than, say, fix your system or add a car alarm.)

Here's my problems with this scare-via-press release:

I don't know of any operating system and laptop combo that keeps a machine awake for long after the lid is closed unless the OS is highly misconfigured or there's an error.

Wi-Fi detectors don't pick up clients to my knowledge, only beacons from access points. (If a client were running XP in its old, bad mode in which ad hoc network names were being advertised, perhaps the laptop would be detectable.)

Laptops in a case in a car would produce very little detectable signal, and the Wi-Fi detectors I'm aware of have very little directionality. 2.4 GHz sniffers with two antennas might be far more reliable.

Apple's Wake on Demand feature relies on a Wireless Multimedia Mode (WMM) option which I have no idea how widely implemented it is beyond Mac OS X 10.6 (Snow Leopard). Wake on Demand keeps a tiny bit of juice fed to the Wi-Fi module to listen for a wake command from an Apple base station, but I don't believe the adapter is broadcasting.

Any other ideas? Or is this just plain scaremongering?

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