FBW is a lot more than just an electronic "connection" between the control handles and the control surfaces.
The Airbus and Boeing FBW philosophies are rather different, and the following fits best on "busses":
A lot of other inputs are fed into the control computers, airspeed, angle of attack etc.
Adverse yaw compensation is automatically calculated, so the pilots doesn't need to touch the rudder pedals until he lands in crosswind.
Drooping ailerons are a pure software issue.
The sidestick control should be regarded more as "give me so and so much bank angle or climb/descend rate" than an connection to the ailerons and elevator.
Software prohibits overstressing the airframe and limits bank angles.
Autothrottle is intergrated in the system.
Airbusses have a very rude mechanical way of bringing a plane down in case of total FBW failure. It has wires to the rudder for yaw and roll control. Also differentiated engine power can control yaw/roll. Mechanical trim on elevator, and to some extent symmetrical engine power, can control pitch. But it is a very tricky job to hit a runway that way. In practice the two pilots will share the job, one taking care of the pedals, while the other one takes care of pitch. That's at least how they practice in sims. Then they pray for nice weather, no sidewind and a loooong runway.
The A380 will not have any mechanical backup since:
1. It is really only waste of good metal for the wires.
2. No human pilot would have the power in his legs to turn the rudder.
FBW should no longer be looked upon as some "extraordinary" control system for airliners. During the last fifteen years no totally new large airliner design has left the drawing board without having FBW control. And it will never ever happen again. The B767 will walk into history as the very last large airliner with mechanical controls designed on this planet.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs