RealSense is Intel's 3D camera initiative for bringing face recognition, gesture control, speech input, and augmented reality to the PC. Its closest analogy would be Microsoft's Kinect for Windows. The technology has been presented at Intel keynotes for a while now, embodied in the "Intel Perceptual Computing SDK 2013" under its "Perceptual Computing" initiative.
Since August 31st, that has been removed from their site and replaced with the Intel RealSense SDK. While the software is free, you will probably need compatible hardware to do anything useful. None is available yet, but the "Intel RealSense Developer Kit" hardware (not to be confused with the "Intel RealSense SDK", which is software) is available for reservation at Intel's website. The camera is manufactured by Creative Labs and will cost $99. They are also very clear that this is a developer tool, and forbid it from being used in "mission critical applications". Basically, don't trust your life on it, or the lives and health of any other(s) or anything.
The developer kit will be available for many regions: the US, Canada, much of Europe, Brazil, India, China, Taiwan, Japan, Malaysia, South Korea, New Zealand, Australia, Russia, Israel, and Singapore.