If you're going to take pictures of the screening area, be discreet about it. Look like a tourist, get in very early, carry tickets, boarding pass, book or newspaper, MP3 player, choose a nice spot, wait, and take pictures.

Virtually every airport in the US has a nice waiting area with chairs past the "checkpoint".

Think ABC news leaves their cameras out when they're going "undercover" for a story? No, it's hidden in a bag, and so should your camera.