According to an article in The Hollywood Reporter, a marketing executive who happened to meet Andrew Breitbart just before he died recounted a conversation he had with the blogger. The two apparently met in a bar at The Brentwood restaurant, began talking politics, and parted a little less than two hours later. The exec, Arthur Sando, was likely the last person to talk with Breitbart.
Sando said Breitbart sipped red wine during their conversation, was on his Blackberry a lot, but was not drinking heavily or showing any sign of health problems. The two talked about the current lineup of Republican candidates, Breitbart's appearances on Bill Maher's program, and then exchanged contact information and parted.
Breitbart, who had a history of heart problems, suffered a heart attack shortly thereafter, perhaps walking home from the bar.
Speaking of Breitbart's appearances on Maher's show, here's a sample (brief "language").