As we already know, the MXM graphics module is NVIDIA's answer to discrete graphics integration in notebooks. The MXM is essentially a scaled down PCI Express interface which attempts to be a standard interconnect for discrete graphics solution used in notebooks. MXM is an initiative by NVIDIA, so it's natural that you'll find only MXM modules based on NVIDIA's GeForce Go GPUs.
MXM has many benefits and its flexibility will obviously help notebook manufacturers offer systems with various kinds of graphics. Besides that, MXM will also allow graphics upgradeability in a notebook as it has done away with proprietary graphics interfaces. The MXM electromechanical specification also detailed the size of the MXM module along with its retention mechanism and cooling requirements. All these standards have made it possible for notebook manufacturers to adopt MXM as the standard graphics interface for their notebooks and obviously reducing the manufacturer's development time. In fact, according to NVIDIA, MXM is an open standard and ATI is free to use its specifications as well.
Now, what is MXM SLI then? Well, as its name implies, it's SLI using two MXM modules - it's that simple. It seems that MSI has found a way to put two MXM modules together in an SLI configuration without the need for any complicated hardware modifications on the MXM modules. As we found out, MXM SLI is just as simple as putting two MXM modules together.
Here's a quick preview of MSI's prototype MXM SLI card which will be showcased at CES 2006 :-