Well, trends shown on Twitter itself have self-reinforcement effect: once a trends breaks into the Top 10, it's snowball after that. Thus, it's not sufficient to just study tweets when identifying trends. Breaking into the Top 10 is a major event.
Thus I suggest Twitter carefully records when it changes the Top 10 display and provides it via an API! This is a separate, computational processing which affects almost every Twitter user's behavior, and is thus important to preserve and study. Cheers, Alexy
