What I don't understand is this: Why do companies (like four square, twitter, etc) wait until after their first multi-hour crash before instituting a "this is how we'll communicate to users when we have downtime" process? I would assume that everyone has learned from twitter's historical mistakes at this point. I would argue that startups -- especially startups that deal with large numbers of transactions per day -- start with code and policies for communicating downtime issues first and launch the product second.