Not that I seriously question the accuracy of that statement, but I recall seeing an article on that very same subject posted on FR here during last year's presidential campaign.
Seems as if all the evidence that has been mustered for supporting his possible attendance at Columbia is an article written by him on disarmament in the campus publication "The Sundial." There is also a photo of him posing with his grandparents that appears to have a NYC background, but that would only show that he was in NYC about that time; it bears no direct connection to Columbia. The same holds for a photo of Obama posing with his supposed Columbia roommate in what purportedly was his NYC apartment.
Obama’s 1983 College Magazine Article
http://documents.nytimes.com/obama-s-1983-college-magazine-article#p=2
Breaking the War Mentality (Obama article from 1983 — full text)
Sundial (via NY Times) ^ | March 10, 1983 | Barack Obama
Posted on Monday, July 06, 2009 12:30:40 PM by
http://www.freerepublic.com/focus/news/2286251/posts
That photograph of Obama on a bench in New York’s Central Park is photoshopped.
1. He has on his wedding ring. He wouldn’t be married until years later.
2. His grandpa’s left hand is ‘floating’ over Barry’s left shoulder but grandpa’s own left shoulder is positioned so his arm would be down at his own side, not extended outward.
People out there who regularly use Photoshop can probably find even more irregularities.