It depends on if Apple is using a 64-bit filesystem on some of the newer systems. Can't say as I know for sure. Even if it's still a 32-bit filesystem, it should be able to handle drives up to around 4TB. Maybe not a full 4TB, but pretty close. If it's a 64-bit filesystem, then it should be into the peta or exabyte range, maybe even decabyte.
does anybody know what is the maximum hard drive capacity a MacBook Pro can handle is? I have heard 250 gb, but I am unsure.