Originally posted by cubist
What you're describing is not a Cube but a Shuttle, but perhaps a bit larger for two HDDs and two graphics card slots. The Shuttle form-factor is great - I've got two of them. As for the dual HDDs and SLI, very few consumers use more than one HDD, and SLI is of interest to virtually nobody (fewer than .001% of computer users). Shuttle's been making machines for years, and they don't appear to have had much demand for either feature.
I doubt Apple will make such a machine. They are concentrating on what sells right now, and that's notebooks and iMacs. They do need a headless machine, and far and away the most popular type of headless machine these days is a standard minitower, so that's what I'd expect.
The difference between what Apple has access to now vs what they had access to before, could herald a difference in their plans.
Previously, they had a rather stark choice. A G4, fast becoming obsolete, and the G5 pretty fast, but slightly behind the Xeon, and further behind the Opteron, because of lack of development.
Now, they have access to a number of chip families.
This can lead to a change in thinking at Apple. With everything from ultra low voltage single core portable chips, to high end dual, and shortly after, four core monsters, Apple can finally design machines that they simply couldn't before.
I don't think that we should rule anything out anymore. There is no reason why Apple must stay within the boundaries it's been restricted to previously.
With the market now opened up to the PC world as well, where people are used to seeing a larger number of models, Apple could greatly benefit by taking advantage of the opportunity to cater to more groups that it has been able to before.
If you look at the catalogs of the largest manufacturers, you will see that they have quite a few more models than Apple has. While I'm not saying that they should go wild here, I am saying that another line in the desktop area, and another line in the portable area wouldn't hurt, and would be beneficial to those who just don't find Apple's current offerings appealing.