Well, Bummer! After another check on Apple's website, it appears that the maximum ram I can have is only 3GB. This kind of fits with my general history of computer upgrades though. For every Mac I've owned, I usually do one major OS upgrade (10.6 in this case), and by the time I get around to another major upgrade (10.10), the computer is sufficiently obsolete that I might as well buy a new one, with the new OS already in it.
Add to that in the newest Macs, including the Mac Pro the memory is soldered to the logic board and cannot be upgraded ever. What you buy initially is all you will ever have. There is a lot of sound engineering behind Apple's decision to do that, but it does change one's thinking when purchasing a new Mac.
