If you are an experienced C programmer (and there are many out there)
- you are working directly with the machine(s), so you already have some mental
abstraction for a (hardware) machine. This puts you in a good position to
appreciate what a virtual machine has to offer.
- you have been bitten by memory leaks and out of bounds array acceses, so you
can appreciate the protection Smalltalk offers for these.
- you have suffered because of long and separate edit/compile/link cycles, so
you can appreciate incremental compilation.
- you know what pointers and structures are, so you can gain a solid
understanding from the grounds up (the VM and the method cache and the JIT and
the garbage collector and the primitives and the image structure and the object
representation are all very C'ish)
- the Smalltalk syntax is very simple and after you understand how Smalltalk
works  you can start playing with it from a VM hacker's perspective - which is
very appealing.
- you can be introduced early to "difficult" Smalltalk aspects (Process,
Semaphore, Context, CompiledMethod, Block...)

I am sure the list goes on.
Such a book would make  a very interesting read (it should be called "Smalltalk
for hackers" though)



Florin