The JPL hopes that FINDER will be ready for use during the summer of this year.
http://www.accuweather.com/en/weather-news/cuttingedge-radar-to-help-save/21433489
Another article with a bit more detail and a video of how it works:
http://www.cnet.com/news/nasa-radar-device-detects-heartbeats-in-disaster-rubble/