Coming internationally Q2 2017. http://www.bit-tech.net/news/hardware/2017/01/05/htc-tpcast-vive-tracker/1
Not going to touch this with a bargepole until some independent latency testing has been performed. The SiBeam WirelessHD chipset they're using is well over a year old, and was intended for use in AV receivers and similar rather than HMDs (has a power draw of a few watts, hence the jump vents on the TPCast and short battery life from such a large battery).