[tankenmate]

In this case since the warrant probably didn't allow for the seizure of Instapaper's servers / data you run a serious Fourth Amendment risk of any evidence within being inadmissible. That said even if it is inadmissible the FBI now know things they might not have known before. There is the obvious point that there is very little likelihood of any direct evidence of a crime in Instapaper's data, there maybe indirect or circumstantial evidence though.