snopes.com:

"Although Barack Obama may not have been particularly social or memorable during his years at Columbia, it isn't true that "no one ever came forward from Obama's past saying they knew him, attended school with him, was his friend, etc." Those who have attested to having daily personal experience with him during his time at that school include:

    Friend and roommate Sohale Siddiqi, whom the Associated Press located and interviewed in May 2008.

    Roommate Phil Boerner, who provided his recollections of sharing a New York City apartment with classmate Barack Obama to the Columbia College Today alumni publication and the New York Times in early 2009.

    Michael L. Baron, who taught the year-long honors seminar in American Foreign Policy that Barack Obama took during his senior year at Columbia and recalled in an NBC interview Obama's "easily acing" the class and receiving an A for his senior paper on the topic of nuclear negotiations with the Soviet Union.

Likewise, other external evidence documents Barack Obama's presence at Columbia from 1981-83, including:

    An article by Barack Obama published in the 10 March 1983 edition of Columbia's Sundial school magazine.

    A January 2005 Columbia College Today profile of Barack Obama as a Columbia alumnus.

    A Columbia College press release from November 2008 identifying him as "the first College alumnus to be elected President of the United States."


Read more at http://www.snopes.com/politics/obama/columbia.asp#pcpST0Cg5lhqIMdK.99"

You really should read more widely SWronger.