Personally, I prefer proximity unlock, I shouldn't have to touch the phone at all. This might be done with Bluetooth LE devices, the same way modern keyless entry works for cars.
If my phone is within a meter or two of my keychain, or I'm in my car, then it is unlocked. This is especially important if you want to use it while driving via voice and don't want to have to unlock after each interaction.
Ditto for Moto-X style notifications. I shouldn't have to press the home button to see that tweet that just came in, in fact, I should be able to ask the phone to read it to me, through my headphones.
The fingerprint scanner is definitely a step up from 2-N touches (swipe to unlock + passcode), 1 touch is better than 2*, but zero touches is even better in some circumstances. Never having to think about needing to unlock.
The number one place I would want security on my phone, would be at a bar (or party), where someone might take my phone when I'm distracted, and then doing either something innocent ("lol. im gay. party hard!!!") or nasty (transfer $100 to own account), depending how well I know them. This could easily be done within a meter or two of me, without me noticing. Adding some rules could be nice (be in car, charging at home etc), but generally, I would want my phone to be locked unless I'm holding it.
That's what I'm worried about with Touch ID. The new "draw a penis on someone's forehead when they're passed out" is going to be "unlock their iPhone with their finger and post things on their Facebook".
You can do this quite easily with Tasker[0]. At home, you could use the presence of your home wifi network as the indicator that the lock should be disabled, while in your car you could use a passive NFC tag (about 50¢).
How about proximity + voice print or proximity + face unlock. It's basically 2-factors. Maybe this is the use case for Google Glass, retinal unlock just by looking at the screen.
And if you want to use your phone in the toilet you need a Bluetooth Beacon in the toilet. Moreover all these beacons must somehow remain synced with your identity, so more cloud, more sensible data stored on big companies servers.
In summary, I think beacons are useful but I think the most interesting stuff is for a smartphone to unlock a car not the other way around.
If my phone is within a meter or two of my keychain, or I'm in my car, then it is unlocked. This is especially important if you want to use it while driving via voice and don't want to have to unlock after each interaction.
Ditto for Moto-X style notifications. I shouldn't have to press the home button to see that tweet that just came in, in fact, I should be able to ask the phone to read it to me, through my headphones.
The fingerprint scanner is definitely a step up from 2-N touches (swipe to unlock + passcode), 1 touch is better than 2*, but zero touches is even better in some circumstances. Never having to think about needing to unlock.