Good question Maalox! Click on the last link "FEMA" at the bottom of this page which will take you to the MD forum. There's some good information posted there regarding FEMA. Basically, it seems the FEMA sets up temporary repeater sites in disaster areas and coordinate with local FD and PD. These temporary repeaters are mostly scrambled or P25. FEMA also enjoys using cell phones very often as well. It would be very hard to actually pick up a conventional frequency used by FEMA anymore.
Ben