AXA Integrated Lock
The intergrated AXA locks are useful and ridiculously simple to use for quick trips into the store or coffee shop where you can keep an eye on the bike. Also great for keeping it from disappearing or being hijacked by curious 8 year olds while you're at the playground or park. The key stays in the AXA lock as you ride, so locking is as simple as turning the key and sliding the lever on the opposite side down until it clicks and then removing the key. Anyway, the AXA isn't the total security solution given the rampant bike theft we're seeing in Portland, but a thoughtful addition to a citybike that makes many small errands like dropping mail at the post office a lot quicker and less involved.
Cargobikes are heavy and unwieldy enough when the rear wheel is locked that it would be hard to drag off, though 2 or 3 people could certainly pack one off into a pickup or large van given the chance. I would definitely recommend a strong U lock like the Kryptonite New York series for when you'll be away longer.
Here's an interesting article from Cambridge on AXA locks. Too bad we live in world where we have to lock bikes at all...