It's standard procedure to inform jurors to remain mum and not conduct any research about the case until a verdict.
Recent gadget use by jurors has forced the hand of the Judicial Conference of the United States, the policy-making body of the federal courts.
The Judicial Conference released the following instructions to the federal judiciary in late January:
You may not communicate with anyone about the case on your cellphone, through e-mail, Blackberry, iPhone, text messaging, or on Twitter, through any blog or website, through any internet chat room, or by way of any other social networking websites, including Facebook, MySpace, LinkedIn and YouTube.
More here.