Peter Schiff, son of the imprisoned author/tax protestor Irwin Schiff, has been a very vocal critic of Bitcoin. He has appeared in many debates with Bitcoin evangelists. He has always been a strong advocate of hard assets, specifically precious metals over crypto-currencies.
His company which sells gold and silver just began accepting Bitcoin, though he claims he still doesn't believe in it.
In this video, Max Keiser has some fun calling out Peter Schiff on his stance then goes on to discuss the importance of Darkcoin and interviews one of the developers of Dark Wallet.
This is well worth watching in its entirety.