What is Reamping?
Reamping is a particular miking method that consists in recording first some raw, unprocessed guitar or bass sound, and then in sending that recorded sound into the device of one's choice. That device will typically be an amplifier, hence the term "reamping", but it can also be a speaker-cab and microphone.
The point is that you can re-work your sound after you have recorded it. The Torpedo thus allows you to record the sound as it comes out of your amplifier, and then to have it processed by the miking simulation. It can also all be done numérically.
Note that the 2012 version of the Torpedo VB-101 already includes the Dual Miking feature, which allows you to combine two cabs and two mics without having to go through reamping.
For more information on reamping, please refer to the excellent WIKI article here: http://en.wikipedia.org/wiki/Re-amp