Ole Miss Debate Switch-Up?

I had been under the impression for months that the presidential debate in Oxford, the first of the four (including the VP debate) agreed to by the two campaigns, would focus on matters of domestic policy and the economy. Today's joint statement from the Obama and McCain camps switches it up, though:

Summary of McCain-Obama Debate Agreement

The two campaigns agreed today on a framework for four General Election debates, to be sponsored by the Commission on Presidential Debates. Key elements of the agreement are:

First Presidential Debate:
Date: September 26
Site: University of Mississippi
Topic: Foreign Policy & National Security
Moderator: Jim Lehrer
Staging: Podium debate
Answer Format: The debate will be broken into nine, 9-minute segments. The moderator will introduce a topic and allow each candidate 2 minutes to comment. After these initial answers, the moderator will facilitate an open discussion of the topic for the remaining 5 minutes, ensuring that both candidates receive an equal amount of time to comment

Well, at least that means the snaking hurricane fencing that's been going up over the last month or so, gradually encircling the debate grounds (and a pretty sizable buffer zone too), will match the content of the discussion.