There are currently two Thunderbolt controllers available from Intel.
The Light Ridge controller chip is the larger of the two with four 10Gbps bi-directional data channels and two DisplayPort connections. It is used in the Apple MacBook Pro, iMac and Mac Mini.
The smaller Eagle Ridge chip has two 10Gbps bi-directional data channels and one DisplayPort connection. It is available in SFF (small form factor package) and is used in the Apple MacBook Air.
The new Cactus Ridge Thunderbolt controllers are due to be released this year, coinciding with the release of the Ivy Bridge platform.
They will come in 4 channel and 2 channel versions like the current controllers but will be the same size.
Both will be available in a 12 x 12mm package, which is about the same size as the current SFF Eagle Ridge controller chip.
It’s hoped that due to the lower production costs, they will be cheaper so will encourage wider adoption of Thunderbolt technology.
It is also speculated that there is to be a third Intel Thunderbolt controller chip featuring a single 10Gbps bi-directional data channel. Known as Port Ridge, it will be only 5 x 6mm in size, ideal for smaller mobile devices.
It will however be without support for the pass through of Thunderbolt signals, so would be most likely used as an endpoint device.