I'm not sophisticated enough to know if it would be an issue with the Kistmet binary or with the wifi driver... but I do know that the Symbol card in question worked fantastically well with Kismet under OpenZaurus, so it cannot be a problem inherent to the card, the Zaurus, or Kismet.
Come to think of it, it probably is the driver, because it doesn't seem to be possible to set the transmission strength* of the card under pdaXrom, while it is under OpenZaurus.
Issues like these are making me increasingly inclined to switch ROMs.
* Yeah, I know, you wouldn't think that transmission strength would affect Kismet's ability to discover networks**, but it does. Maybe the setting does more than the name suggests.
** Or maybe you wouldn't think that. I would.