Mini PCI is a new standard which measures at 2.75-inch x 1.81-inch x 0.22-inch is a new standard developed by leading notebook manufactures.
This technology could allow manufactures to lower their price as the motherboards would be simpler to design.
Type I - Identical to Type II, except requires extra cables for for connectors like the RJ-11 and RJ-45. However, offers more flexibility to where it can be placed in the computer.
Type II - Used when size is not important. Type II is able to integrate the RJ-11 and RJ-45 connectors and due away with extra cables.
Type III - SO-DIMM style connector that can be installed with a mere 5 mm overall height above the system board. In addition cabling to the I/O connectors allow Type III cards to be placed anywhere in the system.