This looks like the one many MCS owners have been waiting for (from the official MINIUSA Bulletin):

Aftersales is pleased to announce the release of an auxiliary Gauge Kit for the Mini Cooper S.

These gauges are a must have for every enthusiastic Mini Cooper S Driver. The kit contains a volt meter and a mechanical boost gauge. The boost gauge is specially calibrated to match the stock Mini Cooper S as well as the Mini Cooper S with the John Cooper Works Kit. The custom made gauge pod positions the two gauges, where they are most visible, next to the rev-meter on the steering column, right in view of the driver.

The silver face plate with the black scale and the silver bezel blend perfectly with the MIni interior. The gauges come with a “Cooper S” logo on the face plate and special back lighting to match the other Mini instruments.

Suggested install time 1.5hrs

Mini Auxiliary Gauge Kit part #82 94 0 393 994 MSRP: $325

NOTE: The kit CAN NOT be installed in combination with the optional Chrono Pack(SA547) or the Navigation System (SA609)

Photo via MINI of Peabody. Also a big thanks to Paul C. for the info.