I have a theory that one of the things that makes twitter appealing to many people is it's ephemeral nature. Seen this way it's historical flakiness is actually one of the the things that makes it popular. Whether valid or not, there is a sense in which twitter seems to be a good venue for casual social messages that aren't going to be archived and potentially used against you at some later date. Whereas facebook (ag…
Plus, there have been numerous documented instances where deleted tweets can still be found by Twitter's own search engine.
In short, the old rule of thumb still applies: if you don't want it archived and indexed and preserved forever, don't put it online in the first place.