As Twitter develops, the service's users are pushing the envelope beyond the company's initial expectations - taking what was supposed to be vanilla status updates to a small group of friends, and extending it to include features that are practically standards at this point - including replies from one account to another, and retweets. But some of the discovery to find related items from one tweet to another can be very hard. Individual users can see mentions, and with some work, Twitter Search can be useful, but for the most part, individual updates are disjointed pieces of conversation.