Twitter's REST API returns a in_reply_to_status_id value for tweet statuses, yet the Search API does not.
What puzzles me is, if you search using the http://search.twitter.com/ webpage directly, tweets that are in reply to another tweet contain a "Show Conversation" link, but when searching using the API directly, there doesn't seem to be any data suggesting that a conversation exists (with JSON, at least).
How does this search page know which tweets are part of a conversation, and what would be the best way to emulate this behaviour (JSON preferred) in a rate-friendly way? I imagine I would have to do additional calls or something...?