When the transactions to or from that address happen then the transactions all go into the block chain.
Thanks for replying. So you're saying that the addresses created by the bitcoin client don't exist on the blockchain until come coins are transferred from that address, and once coins are transferred the sending address will exist on the blockchain in addition to being on the client? Does that address stay on the blockchain from then on? Is there some mechanism that prevents two different clients from coincidentally making the same address?