Picked up a new entry in my firewall log today that I've never seen before. I'm sure all you guys know of this but it's new on me: an XMas scan.

Stealth scanning is used by intruders to discover what ports are listening on a machine without being detected. A TCP FIN, or Stealth FIN, scan will send a FIN packet to each port. A Xmas Tree scan uses packets with the FIN, URG, and PUSH flags set.
So what's this all about? Is this something I need be concerned about, or just more of the usual auto scanning going on out there in the wild?