[aychedee]

There is no transition required. When send an amount of bitcoins to another address you specify how much of a transaction fee you are willing to pay to the miner who solves the block of transactions your transaction will be included in. Any given miner can prefer to solve transaction blocks with higher fees. Eventually it will get to the point that if you don't include a transaction fee your transaction will just be ignored and not included in the block chain. At the moment it will probably be included anyway because of the inherent reward for creating a valid transaction block.