That, at least, shouldn't be the case. Your conversations live in the Notifications tab.
I ended up questioning some news anchors for an hour yesterday on one of the feeds, and the thought hit me about how much better this was than just the news.
> ... when you do actually get a conversation
> going, it's hard to follow ...
That's why I wrote some scripts to do this:http://www.solipsys.co.uk/TwitterConversations/HeliumBalloon...
http://www.solipsys.co.uk/TwitterConversations/ListContainin...
Now, with the recent articles about Twitter's apps collecting the list of applications you have installed on your mobile, I tend to think that Twitter is as broken a concept as 'You can shout 140 characters - but no more - and people need to reply just as terse' sounds to your granddad. There's no way to justify the crazy limitations and the owner of the platform turns out to be another FB.
Next up: Real name policies on Twitter?
Can break down with sub-conversation trees a little, but that's hardly only twitter's problem. I'd be more than happy with reddit-style @reply threads.