Yes!
WD-40 Multi-Use Product contains a 360° ball bearing value; a mechanism that allows the can to be used upright or upside down. There is also a small opening (a tap hole) at the very bottom of the valve. In the valve is a small ball bearing.
When a WD-40® can is held upright, the propellant is at the top, and the liquid at the bottom of the can. In this position, the ball bearing blocks a small hole in the valve, allowing the liquid through the bottom of the dip tube. When the can is held upside down, the propellant is at the bottom of the can and the liquid is at the top. In this position, the ball bearing blocks the bottom of the dip tube and opens the valve at the top, in contact with the liquid, is now open. For more information on how to get the most out of the can, see this guide.
The worst position to hold a can of WD-40® is sideways. Here the ball bearing blocks neither hole, and you lose a substantial amount of propellant (escapes much faster than liquid). When all the propellant is gone, the aerosol will no longer function.