I am not an expert but if the 8 GB RAM capacity holds then I suspect it has to do with 8 = 2^3. I can see possibly three banks each with 2 slots to hold up to two 1 GB SDRAM.
I agree that some of the software is getting HUGE and I can forsee 1 to 2 GB programs which are fastest and most efficient being held all in RAM. The other side of the coin is that virtual memory involves flipping one or two pages (usually 512 bytes of data and instructions) in and out of RAM memory.
Its been a long (30 years) time since I worked on virtual memory design and memory hierarchys so who knows.
By the way, from the previous posts, I stand corrected in my assumption that Apple was hacked into to produce an erroneous web page. Well, Monday will tell the tale. If it is all true, I know that I will immediately order the biggest and baddest cruncher Apple offers. (Kris please forgive my garmmatical errors).
MamaMoose