Navigating Risk

I've taken a few cabs lately and all have had the tom tom.  I can see why they'd want to employ such a relatively cheap device to reduce the 'risk' of their knowledge being exposed.  But what has sat nav technology done to the kudos of the taxi driver in exposing their uncertainty?  What has it done to 'the knowledge', the cornerstone of their reputation and business?  Are knowledge tests now redundant?

I also find it interesting how people, particularly women travelling alone, are using cameraphones to take images of cab drivers / driver licenses when taking a cab home to mitigate the risk of attack or abuse. 

What other social uses does the cameraphone and the 'image' have in discreet social situtions to help us stay safe?  Occasions / need states anyone?  I've seen people use them when they've been in an accident - but that doesn't require the upload of the image to a remote server necessarily, it can stay 'local' to the phone itself.   I guess things like tickets, reference numbers, identifiers of all sorts when moving about would be handy to capture in case you lost them and your phone.   With 3G providers desperately looking for need states and 'killer apps' it may be worthwhile looking at social risk as much as social pleasure [entertainment] to sell their services.