In an article written January 13, the episode of Smallville that was originally scheduled to air tonight is described as "eerie how similar this storyline seems" to the shooting of Representative Gabrielle Giffords.
"However, logic dictates that this episode of Smallville will be preempted. Given the way the Giffords shooting has impacted the country, to have TV show feature a plot line about a congresswoman getting shot at a rally would be in bad taste, even if it is a super hero fantasy series."
This could be the reason that the CW decided to postpone Smallville and Supernatural to next week.