Smalltalk is a family of dialects and implementations. Most of them are indeed compiled to bytecode which is then executed by a JIT VM. Most of them use the "image" concept where you are always in runtime like in a classic Lisp, and yes, the VM handles shape changes etc etc. But some Smalltalks actually have other characteristics, like non JIT or even compiling via C (Smalltalk/X does that I believe).