Here are some details taken from the official press release:

Video Array is an accelerated graphics processing subsystem that will allow users to add multiple, off-the-shelf video cards to their Alienware computer systems and have both cards process graphic commands in parallel. Understanding the wide-ranging wants and needs of its customers, Alienware designed its solution so that it is not tied to any one specific video card.
This design will allow users to take full advantage of the fastest video card on the market for a significant performance increase.

Alienware's exclusive Video Array combined with X2, an Alienware-designed motherboard which is currently based on Intel Corporation's next-generation chipset and will include dual PCI-Express high performance graphics card slots, will deliver significant performance gains over current graphic solutions. The new Video Array Technology and X2 motherboard will enable users to run graphics intensive applications flawlessly at maximized settings, render 3D visuals in record time, and much more.