True threaded SMS will show only a single SMS in your inbox, and when you click on it to open it you see the entire conversation laid out like an IM chat. Rather than create a separate message for each response it adds to the current conversation. After typing 10 responses to 10 incoming messages your inbox still shows the one message, not a pile of 20 individual ones. Nobody does SMS like the Palm Treo. Unfortunately, that's about all they do well.