[hackinthebochs]

>for example, if you nest Serpent inside AES for a single local file encryption operation (ahem, TrueCrypt), that seems very gimmicky.

I take it to be insurance against a future vulnerablility discovered in one of the algorithms. For some scenarios it seems like the cost can be worth it.

On the other hand, nested hashing has always seemed counter productive as it seems plausible that nesting hash functions can decrease the randomness of the image.