Ok, so people who know me, will know that I think RAM is pretty cool stuff, and that you cant really have enough. OK, so you can have enough, but it is very handy stuff.
A register article today was talking about how MetaRAM can now get 288GB of RAM in a single machine. As someone quickly pointed out in the comments, Sun Microsystems have a machine out for almost 2 years now which supports 256GB of RAM. Its an x86 machine called the x4600. Sun also sell a SPARC machine called the M9000. It supports 2TB of RAM. Thats 2000GB of RAM. Oh, and its got 64 processors.
People should really not be surprised that the limit of how much RAM they have, is not to do with their choice of hardware, but rather choice of Operating System. At this time of writing, thew most advanced version of Windows Server 2003 (Datacenter Edition) CAN address up to 2TB of RAM. But because its written for the x86 architecture, you’ll struggle to run it anywhere to address it all. I should imagine that its partly to do with market demand; you can be sure that if customers were crying out for high capacity x86 equipment, the manufacturers would be making it. Maybe Microsoft should make a port of Windows to run on SPARC? 
I find that on the whole this is quite typical of Sun. Their hardware can cost more, but it comes out earlier, and its better than kit in the same class. Sort of like Volkswagen or BMW. Higher cost, but higher quality, and more innovation.
Tags: M9000, RAM, Sun Microsystems, x4600, x86
Ahh but if we could get 16GB DIMMS into the x4600 we could get 8 16 GB DIMMS on each CPU board to make 128GB per board, with the maximum 8 CPU boards we could get a 1TB into 4u - that would be truly cool!
You see, again Sun breaks barriers with a huge sledge hammer, not just a little pin hammer. Mind you, the reg article said it was with DDR3 technology,I don’t recall which the x4600 uses, I’ll check it out and report back!