Why is John McCain in Colombia? The most reassuring theory I can come up with is that McCain intends to bring back a couple of sixty pound suitcases that the Secret Service will hustle for him through Customs. And soon Obama's big lead in campaign finance will have vanished. And there won't be anymore questions about McCain being too old to have the energy for the job as he starts campaigning 96 hours straight.
On the other hand, there are more alarming interpretations, such as that McCain is taking a serious interest in the geopolitical situation in Northern South America -- i.e., he wants to get us involved in a war there.