Of course the usual obfuscators showed up within the first few comment posts. And the usual conspriracy freaks. According to one of them, you can recover files via a one-to-one bit copy even after the original had been overwritten ten times.
In an odd twist of timing, tonight's class worked with Helix to gather data from a running system. For those that don't know what it is, Helix is a Linux-based "live CD" that also is devoted to obtaining forensics data from live systems and making bit copies of storage devices. In addition to being a "live cd", you can also drop the CD into the drive on a running Windows system. "Autorun" will bring up an interface with a set of statically-compiled tools which allow you to perform various forensics functions (see the site for more info).