http://www.iwill.net/product_2.asp?p_id=102&sp=Y 64 gigs eh? Why anyone, even those workstation dudes would need that much memory in one rig is beyond me but this would be one amazing PC if you maxxed it out. 32 seems like the happy medium judging by the price though.
Probably not many companies, but the capacity is there, because, well, the Opteron's support it and that there are companies that can make use of the capacity, or want the option to upgrade to that point down the road.
Wouldn't it be more efficient to have a bunch of computers with like 16GB's or ram rather than one with 64? Seems like a much more efficient process but I suppose if the sky's the limet why heck not.