I'm I out of contact with what 64 bits means?
Yes it does means that it is able to address 64 bit addresses, but it was also my understanding that 64 bit chips also have registers that are 64 bit wide, and instructions that can work on 64 bits at a time. For example intead of performing mutliple 8 bit operations or 4 16 operations or 2 32 bits operations, it instead executes 1 single intruction able to operate on all 64 bits in that clock cycle.
Has this change and now all they do is perform on large address spaces?
If that is the case, it's not worth as much.
Yes, the x86_64 architecture also increases all general-purpose registers to 64 bits, and adds the ability to perform atomic 64-bit register-to-register (and register-to-RAM?) operations. It also adds a greater number of general-purpose registers than can be accessed by the IA32 architecture (or 32-bit mode processes running on the x86_64).
This is tied in to the common principle that sizeof(int) == sizeof(void*).
Of course, the 64-bit virtual address space and 64-bit atomic integer size are both inextricably tied to the presence of a 64-bit processor (but as has been very thoroughly pointed out, it has nothing to do with the width of the address bus which physically interfaces with the outside world), so all of us early adopters and un-modded Mac Mini users will still be working in a purely 32-bit world.