Briefly: Senator Mary Landrieu (D-LA) has endorsed the concept of pulling FEMA out from the Department of Homeland Security. I personally disagree from a philosophical standpoint--the idea is to integrate all of the services that might be involved in any sort of an emergency, be they law enforcement or humanitarian--but as its a bureaucratic decision, I think that's best decided by the people in the federal bureaucracy.
Basically, it comes down to this: is the greater synergy of a larger more centralized department necessary, or can they streamline communications better as separate departments, each of which are able to tackle their own objectives more effectively? I can't answer that because I don't work there, and I don't think pundits should either. If the answer is the latter, than the Deparment of Homeland Security should probably be dissolved entirely. I think at the moment there's a clutter of folks with conflicting portfolios. Who is the person most tasked with national security--the Secretary of Homeland Security, or the National Security Advisor? But if DHS really does maximize synergy in a way that department separation restricts, then it should be preserved. Again: that's a bureaucracy call. We should just measure it by results. After all, FEMA's failure during Hurricane Katrina had less to do with the bureaucratic shape of things than simply the choices made by the management.
One more point, from a purely political (and therefore, hopefully, irrelevant from a decision-making standpoint) observation: Governor Napolitano's experience that supposedly prepares her to run the DHS is twofold: one is her efforts securing the border, and the other is her state's response to flash floods and fires. The latter half of her experience goes to waste if FEMA is taken away, and then Napolitano becomes a very ICE-based governor.