HardwareZone had an exclusive look on MSI's first MXM SLI graphics card, here's clip from their report:

Until about two years ago, mobile graphics subsystems have always lagged the mainstream dedicated graphics cards on the desktop, let alone the top-end gaming cards. This gulf in graphics processing capability mobile front was solely due to technical and cost limitation issues that revolved around reducing the footprint required, graphics interface as well as cooling the dedicated graphics unit within the notebook. However, advances in semiconductor process, graphics and packaging technologies together with the standardization of mobile graphics modules since 2004 have greatly pushed forth advanced dedicated graphics options in many current notebooks. Case in point is NVIDIA's MXM graphics module..



Link: Hardware Zone