UPDATE: Hmmm. Five former secretaries of State think we should talk to Iran, including Henry Kissenger, whose opinion I value very little.
The current issue of The Atlantic Monthly, in addition to featuring Ross Douthat's insightful piece on pornography, to which others have drawn attention, also has an insightful article, which articulates what is perhaps the main proportionate reason that pro-life Catholics are either supporting or considering supporting Sen. Obama. The article, by Jeffrey Goldberg, is entitled "The Wars of John McCain".
Another article worth considering is by Fr. John Kavanaugh, SJ, who, after writing a well-reasoned and impassioned open letter to Sen. Obama on the issue of abortion, writes to Sen. McCain about the same issue tackled by Goldberg, in which he tells the senator: "Your problem is a war problem".
You may also find Doug Kmiec's response to Fr. Kavanaugh's open letter to Sen. Obama interesting.