The logic board chipset is still 32bit though.
That doesn't matter. The only difference that a 64 bit chipset would make is to be able to use more than 4 GB of memory. There is only space for two RAM chips. Take a look at what 2 GB chips cost. Now think how much a 4 GB chip would cost you (if you could get them), so nobody could afford an 8 GB MacBook Pro anyway.