"My understanding is, is that the prime minister enjoyed our 312 beer, and we may send him some more," Obama said of the Chicago beer he sent the prime minister. "I thought the beer we got was excellent. But I did drink it cold."
Beer bets aside, Obama said that much of their conversations centered on Afghanistan, where Britain has been the United States' top ally. Cameron has said he wants to withdraw his country's troops by the next election, which would be before 2015.
Obama called the international conference in Kabul today "another major step forward," citing the Afghan government's presentation of plans to improve security, economic growth, good governance and basic government services.
"These are all important achievements, and they go a long way towards helping create the conditions needed for Afghans to assume greater responsibility for their country," the president said. "Indeed, over the coming years, Afghans will begin to take the lead in security and, in July of next year, will begin to transfer -- we will begin to transfer some of our forces out of Afghanistan."
Even as the two leaders tried to emphasize their discussions on Afghanistan and other global issues, reporters focused on BP and the Lockerbie bomber.
Cameron said he understands the anger in the United States aimed at BP over the oil spill, which he called a "catastrophe for the environment, for the fishing industry, for tourism."
The British Prime Minister said he is in regular touch with senior management at the oil company and said that given the fact that BP is important to both the British and American economies, there is a vital interest in ensuring it remains strong and stable.
But Cameron said that there should be no confusion between the oil spill and the Libyan bomber.
"That wasn't a decision taken by BP; it was a decision taken by the Scottish government," he said. "We have to accept that under the laws of my country, where power on certain issues has devolved to Scotland, this was a decision for the Scottish executive -- a decision that they took."
Cameron agreed to meet this evening with a group of concerned US senators to discuss what role, if any, British oil giant BP had in pushing for the release al Megrahi last year.
Cameron had initially declined to meet with the senators, but changed his mind because he "recognizes the strength of feelings" about the Lockerbie bomber, a Downing Street spokesman tells ABC News.
ABC News' Kirit Radia contributed to this report.