If Twitter and Facebook are actually deleting evidence that the DoJ is going to want to see (as opposed to just removing it from public view) that is going to go very badly for both companies and whichever employees made the decision to do so. See 18 US Code 1519, the fines will be massive and prison time can reach up to 20yrs as BigBubba's roomhate.
@Render Do you think it will be enforced? Look at what people are getting away with right now. Flat-out treason. In public. Wha?