According to Television Week, Supernatural, which returns with original episodes on January 15, 2009, will take a break starting March 17 and will be replaced by Reaper. EW.com's Michael Ausiello, however, reports that Reaper will be replacing Privileged. Thanks to Sophy for the heads-up.
UPDATE: E! Online's Kristin Dos Santos is also reporting Privileged as the CW's series to be replaced by Reaper.