I emailed the panelists for the two panels I'm moderating, so can check that off the list.
So far as panel notes go, I'm two books into my Xenogenesis re-read, and have been making notes. Last night I started making notes for the Dr. Who panel I'm on - I need to download some transcripts for eps I don't have on DVD (or that don't exist any more!). I offered to take the First and Second Doctors, having been recently reading/watching a lot of their era. My other panels won't require any research, or not much.
My goal? To be ready well in advance, so my backbrain can chew on the notes I've made and maybe come up with some new insights in the panel discussions themselves.