Facebook co-founder "defriending" America?

Dr. Jon LaPook recalls watching Secretariat become the first U.S. Triple Crown champion in 25 years at the 1973 Belmont Stakes.

New York City's Second Ave. subway was first conceived almost a century ago and when it is completed, it will extend all the way down the eastern side of Manhattan with 16 new stations. CBS News' Don Dahler reports on one of the most challenging public works projects in the country.

The Oxford English Dictionary says "tweet" is now an official word - defined as, "To make a posting on the social networking service Twitter." Gayle King reports.

The U.S. economy is getting better, which could mean more Americans will get married in the next two years. Norah O'Donnell reports.

A driverless boat was left running after the two passengers were tossed in a giant wave off the coast of Saint Petersburg, Fla. Norah O'Donnell reports.

Officials in Colorado have ruled out a natural origin for the Black Forest fire, near Colorado Springs. CBS News' Barry Petersen reports that finding the cause may harder than putting out the fire.

Senior correspondent John Miller talks to the "CBS This Morning" co-hosts about the FBI's essential law enforcement tool, the "Most Wanted" list, which named the 500th fugitive to their list.

The trial of Boston mob boss James "Whitey" Bulger continues, and former hitman John Martorano will take the stand for a second day of testimony after his initial testimony tied Bulger to at least six killings. Elaine Quijano reports.

Passengers aboard United Airlines flight 116 from Hong Kong were forced to tackle a fellow traveler who began screaming about government conspiracies. CBS News' Michelle Miller reports.

Video shows an airport baggage handler in China carelessly tossing boxes onto a conveyor belt. Norah O'Donnell reports.

The FBI continues its latest search for the former teamsters boss. Hoffa was last seen dining with mobsters in 1975. Agents brought digging equipment to a field near Detroit. But so far, there's no evidence Hoffa's remains are there. Charlie Rose reports.

CBS News legal analyst and commentator Rikki Klieman discusses the testimony of a hitman called to the stand in the case of reputed Boston mobster James "Whitey" Bulger, as well as other key witnesses and what to expect next in the trial.