Not directly, but the warm water in the block will mean that at least some heat is immediately available once you start the car. The main benefit of block heaters is not in heating the cab, but heating the engine itself so that it's actually possible to start it.

That aside, never understood the value of "pre heating" the car interior. If it's that cold, you're wearing a coat and gloves (or should be). Start the car, drive off, and you'll have heat within a few minutes.