The fee is currently 0.1 mBTC (~$0.05). While this is not free it is pretty much cheaper than any other payment system.
Credit Cards: $0.30 + 2%
PayPal: $0.30 + 3%
ACH: $0.25 to $0.50
Bank Wire: $10 to $25
International Bank Wire: $25 to $40
Check processing (business): $0.50 ea
etc
To be fair, as much as I do love Bitcoin and what it brings to world transfers.
Debit Card: Usually $0 for a lot of major websites.
Bank Transfer (UK - UK bank account) $0
Bitcoins primary strength is still making small to very large fast transfers across great distances around the world with tiny fees.