[shadowfiend]

You understand that 400M tweets a day is the number of tweets posted to their system, right? That speaks not at all to the consumption of those tweets, which is the metric you're using for your ad platform.

Additionally, they don't just deal with 160 characters, because again, somehow you're still talking about data being posted, and not data being consumed. Data is consumed off their site via polling APIs, streaming APIs, and a website, all of which are pushing those 400M tweets a day out to plenty of consumers.

They may not have as ridiculous a scale as they act like they do. But let's be clear: it is nowhere near as trivial as you make it out to be, either. Armchair quarterbacking is always easy, because you aren't exposed to the complexity that arises when you've spent a few months and years hitting the corner cases of the problem you're commenting on.