Is there a website that explains in detail how one actually redeems the BTC from a coin? Somewhere we can refer coin recipients to?
+10
Do you mean something more detailed than go to MtGox, click "Add Funds", and choose "Redeem Private Key"?
The alternative involves patching source code and is a billion times more difficult. It's out of reach for the average user.
Another method is to use StrongCoin to import the mini key and then send those coins somewhere else. Having a website that explains to average joe what Casascius coins are and how to redeem them would be very helpful.