would you consider dual channel to be "less" sophisticated? we know that the real world implementations do not see that much of an increase in, well, anything! do you see all computers eventually changing to tri-channel? or will we stick/go back to dual-channel?
"Less Sophisticated" = fewer transistors used. The reason, is to make smaller parts for the mainstream market, which means more parts per wafer.
That ultimately translates to lower costs per part. Now they can choose to transfer this to the MSRP, keep it as increased margins, or a bit of both (compromise that makes both sides happy).
As per channels, the mainstream parts will have fewer, as it's not beneficial for such parts. It's the enterprise market that can benefit from it, and where Intel has expanded the channel count on future parts in the Xeon lines.
don't forget TB (which appears to be the same rates for the CPUs), ECC capabilities, and the added security added onto the Xeon chips, dual CPU support of xeons, etc.
Turbo Boost = feature, as is Hyper Threading,... Some, such as ECC, are present in multiple parts, but not Enabled (i.e. i7-920 vs. W3520), and is continued with the newer parts (i.e. Xeon vs. Enthusiast Desktop parts that use LGA1366).
i dont really see how these effect 90% of users of a MacPro - but apple sees the Xeon CPU as an important selling point of their MP.
The reason is because it's the ONLY way to get a Dual Processor system. Desktop parts are impossible to do this with (technical reasons).
There's also the fact that "Xeon" invokes stablity under 100% load conditions in high availability environments (24/7 operation, as you tend to find with servers). Even if it's not used that way, it makes users feel confident that the system is reliable.
I would guess we are going back to dual-channeling as triple-channeling only brings a minor bump over dual-channeling (well, both are pretty useless IMO). Triple-channeling also limits your RAM slots as most computers still have paired number (2,4,6,8) so using e.g. 3 slots out of 4 is pretty dumb IMO.
No. Look at future parts from Intel. They're actually going to scale it up (enterprise grade parts, not mainstream, as there's no need for it).
What you have to keep in mind, is that Triple Channel DDR3 (and expanded versions due in future parts) are meant for servers (i.e. Symetric Multi Processing). This, particularly with software that's been optimized for memory transfers, can actually utilize Triple Channel DDR3
now.
However, as software is almost always behind the hardware, there's precious little that's actually capable of utilizing it ATM (software needs to be updated, and that's going to take time).
If that is reliable, tri-channel provides 50% increase in bandwidth over dual-channel but I think due other bottlenecks, the difference in real life is a lot smaller
It comes back to the software. Most can't utilize it, and some types of applications never will (i.e. "idiot at the other end of the keyboard" reliant ...err... applications that wait for user input

).
It seems a shame to give Windows back the market share OS X fought for during the past decade in such a growth industry.
The devices are where the $$$ is for Apple, as well as the content consumption (i.e. Apps sales and and advertising). As Apple's in business to make money, that's what they're going to follow.
Someone posted that SJ is about the products, not profits. BS IMO. He likes certain products (indictated by the recent focus/comments), but there's a financial motive for him as well. It could be argued job security as well, as if he was making decisions that caused the stock to tank/profits drop, he'd be fired. The Executive Board is all about ROI.