Excerpts from David Maraniss' Barack Obama: The Story dealing with the elaborate drug culture surrounding the president when he attended Punahou School in Honolulu and Occidental College in Los Angeles. He inhaled. A lot.(The Maraniss book doesn't come out until June 19th. You can buy it here.)
ADDED: Here's a long excerpt from the book, covering Obama's college years:
Most of Obama's classmates could not see how hard he was working to reconcile the contradictions that life threw at him. They thought he was cool, smart without being pedantic, and seemed to have his act together. To Mark Parsons, who came to know him mostly because they both smoked and spent a lot of time together huddling outside the student union, Obama seemed "almost Zen in walking through all the chaos in our dorm". He displayed one trait that showed he wanted to be a player though: he wore a lot of "stupid hats". He usually wore them cocked, to look cool. Obama also had a peculiar smoking style, a little affectation. He turned his wrist up and cupped the cigarette between thumb and index finger. He smoked a cigarette the same way he smoked a joint. "I have a sense that he smoked because he was addicted, as I was," Parsons said. But, Obama told Parsons, there was another reason. "I remember him telling me he would quit after he got married. He didn't want to quit smoking because he said he would gain weight, but after he got married it would be OK to gain weight. I think it was mostly a joke."