Still, price and limited autonomy are real issues. At 1K$ and 20 miles of autonomy I would probably buy one.
I have challenged a dozen people to get their bikes locked to a post in the time it takes me to fold the Brommy. No one has succeeded to date.
Still, they are not electric and cost around 1400$
EDIT: This video shows how to fold/unfold one http://www.youtube.com/watch?v=pNnOdoUn3kg . I'm sold!
So how long are we talking about? The video links by the next commenter shows it taking about 20-30 seconds.
I manage to lock up my bike with a simple 4 digit combo chain in less than 10 seconds, but I can get away with locking it to itself in Tokyo :)
That's not why though. One has to get off the bike, get a key out, get the lock out, lean the bike against whatever one is locking it to, put the lock on, and work the key.
With the Brompton, one simply gets off and folds it.
http://us.sanyo.com/Commercial-eneloop-bike
They're just like a regular bike but they assist you when you climb up hills or just plain get tired. The battery behind the seat-tube slides out for a recharge. I would say about 20% of the bikes you see parked by a train station are electric hybrids.
edit: I will say though, that the foldability part of this is nice, but I prefer the hybrid approach of a standard bike.