SLI/Crossfire? Or just plain dual GPU?
I don't think anyone not covered by an NDA knows. There are some claiming the next workstation class Xeon chipset will support SLI because the Skulltrail demos included it. However, the sites that have delved into the Skulltrail motherboards claim Intel is using an nVidia MCP as a bridge to provide SLI.
I tend to be skeptical about SLI and conflicted about Crossfire. nVidia has better graphics cards right now and I believe if Intel had the licensing agreements in place, they would first implement it in the systems gamers buy and not workstation chipsets. They're going to make money on SLI with P35 and X38 class chipsets, not 5000X class chipsets. However, since Intel already supports Crossfire on their desktop platforms, I don't see why they wouldn't eventually bring it to their workstation platform.
As for Apple, I'm skeptical they will support either. The reviews I've read say SLI and Crossfire only make any sense if you're already buying the top of the line graphics card for gaming. Apple has always been very focused on aesthetics and I just can't see them building a system with two 8800 GTX or HD 2900XT cards. You'd never be able to quiet down the system without complex water cooling. Being relatively quiet has been such an important property of Apples for so long, I just can't believe they'd toss it just to say they provide SLI or Crossfire support.
I'm dubious about those people who insist that Apple is missing any significant sales by leaving out better graphics cards and SLI or Crossfire. Of the people I know willing to fork out the money for an 8800 GTX or an HD 2900XT, none want to purchase a prebuilt system, let alone one from Apple. They all build their own systems by acquiring parts. Based on my reading of AnandTech, ArsTechnica and TomsHardware, that seems consistent. The market for those cards is relatively small to begin with, based on sales reports, and the number of those in the market for those cards and willing to buy prebuilt systems is far smaller. I have this feeling that the number of people who
really are unwilling to buy a Mac Pro because it includes an X1900XT but not either an 8800 GTS/GTX/Ultra or HD 2900 Pro/XT is so small it's not worth mentioning.
I think Apple is ignoring the 8800 GTS/GTX/Ultra and HD 2900 Pro/XT cards purely from a financial standpoint. I cannot believe they'd sell any measurable additional Mac Pros to cover the driver development costs so they won't bother until the next refresh that will only run under Leopard.