The Tweet references "pulling video" as well as the promise of an update tomorrow, along with a partially blacked out screenshot, as below.
Surveillance Rpt #274789: Suspect Aiden Pearce was seen on Lake St. ctOS is pulling video, will be updated tomorrow. twitter.com/watchdogsgame/...— Watch Dogs (@watchdogsgame) April 28, 2013
The last Watch Dogs trailer was released in March. Watch it below: