From the first sandwich you ever described in 140-character form to the last joke you tweeted that disappointingly fell flat—by the end of 2012, you should be able to download every tweet you've ever twittered, according to CEO Dick Costolo.
Costolo made the announcement at a recent talk at the University of Michigan, and it seems promising, considering Costolo made the same pledge back in September. So the deadline might actually be attainable. Just don't talk to any of Twitter's engineers about it, because apparently they're not so excited ab out the deadline. Rightfully so—with a billion tweets coming in every couple of days, that's a huge undertaking.