It's taken almost a month for the shooting death of 17-year-old, African American Trayvon Martin to become a national issue. After Florida prosecutors declined to prosecute Neighborhood Watch volunteer George Zimmerman, the story began to go viral on the Internet. It made the mainstream media — producing a demonstration this week in New York City and a rally last night in Sanford, Florida. Today President Obama weighed in, stressing that "all of us as Americans are going to take this with the seriousness it deserves, and we are going to get to the bottom of exactly what happened." We hear about America's expanding gun culture, "stand your ground" laws and the "rules" that black parents teach their sons about how to deal with authorities.