i dont think id ever put that in my mbp, let alone a mb.
as noted in the link, it's more of a pro solution. one of the biggest slow downs on big projects is the prospect of reading and writing to and from the same physical drive. this would be a nice solution for someone who wants that function along with mobility.
i think ive seen somewhere, oh yea, in the system profiler... that there were two sata ports, 0, 1. on 0 was the cdrom if im not mistaken....maybe it was on my macbook. the mbp i have now seems to have the cdrom on ata.