Yeah, but is it art?

Banksy artwork shreds itself after #1m sale at Sotheby's

Personally and for once, I'm at a loss to comment.

Update: I have it on Good Authority that yes, this is legitimately art.

Update #2: You can see the actual shredding happening here.  Banksy shouldn't have cheaped out on the batteries, it looks like they gave out half-way through.

Update #3: Speculation on the internet has it that this incident, its results, and notoriety have instantly increased the value of the work by 2-5x.  We shall see.