I know, this is an audio product, but there isn't as much traffic in the Audition/Soundbooth forum, and I thought this might be of broad interest (I don't own it - yet - and have no affiliation with Sony).
I just took a look at the 15 minute tutorial video and have never seen anything like this! I don't know many audio packages other than Audition/Soundbooth/Acid Studio, so this capability may exist in other DAW types of software. Essentially, you can pull a waveform apart, and put each selected waveform (the frequency and harmonics selection are particularly impressive) onto its own layer, then by adjusting phase, remove the waveform from the original track. Anyway - check it out: