I certainly see where you're coming from and as I say the value for money doesn't quite work out with i7. People buy i7 when they want the best and want a platform that has life in it. The current X58 boards have already been reported to support the refreshed 32nm CPU's with a microcode update for example. I also think that the cost perspective of i7 is exaggerated. Proven boards like the Gigabyte EX58 UD3R can be had for £150 and 6GB Tri Channel memory kits are available for about £20-25 more than a good 4GB DDR2 set. The Core i7 920 can also be had for similar money to the Q9550. Then factor in that most people who are looking at higher end setups want a good P45 based LGA775 board.
Core i7 920 2.66GHz - ~£220
Gigabyte EX58 UD3R - ~£150
6GB DDR3-1600 - £70
Rough Total - £440
Core 2 Quad Q9550 - £200
Gigabye EP45 or whatever P45 board of choice - £100-125
4GB PC2-8500 - £45
Rough Total - £345-370
Percentage extra spent - Up to 28%
Performance Gains? - It depends
So it's not all that outrageous to opt for i7 over a higher end LGA775 set of equipment. I also appreciate what you say about Pro Workstations and CUDA but not everything is graphics card based yet and until it is, the Core i7 see's the bigger gains.
As I say, for gamers, it isn't that straight forward and much of the time, even a high clocked dual core along with a fast graphics card would suffice.
This really has spun out of control and it started from when I picked up on your 0.05% comment but all I wanted to point out was that i7 genuinely does have it's advantages for some, where the additional cost is more than worthwhile.
Returning to the topic at hand, Phenom II / AM3 is where we're going to see all of the interesting stuff on the value for money and gamers side, at least until Core i5 shows up. We have plenty of Socket AM2+ 790GX boards for under £90 and this is where the value is, but as mentioned on the previous page, it'd be nice to see more DDR3 boards. Particularly below £100, as DDR3 doesn't seem to have that much of an effect on this platform