It seems that once the S70 was released it was removed as an optional line-item across the range and was bundled into the final price. However owners of suitable non-S40 vehicles from before that point can still enable access for a fee ( they have the hardware already installed, it's a database flag change ).

"If your vehicle is eligible, the Supercharging upgrade option will be visible in the Available Upgrades section."

http://shop.teslamotors.com/products/enable-supercharging

The S40 has the hardware for Supercharging but is excluded by policy.

I'm only aware of this because a friend in the UK has been trying to work-out what's applicable in this market and Tesla's constant changes to the policy makes that difficult.

Even if it's included standard, it's still priced in though, right? Same reason "Buy three tires; get the fourth free" isn't really free.

I guess we'll find out in 3 days after the Great Supercharger Unbundling occurs.

It is "free with your $100k purchase".