"Not only are Rim (Research in Motion, Blackberry's owner) the most secure messaging operator, they're also the most fastidious - they log everything. If you were a looter using a Blackberry, you're going to get found out. The police have the power to serve Rim with an order to reveal information. Under the same law, Rim are barred from disclosing whether they've done so or not.
But although Rim can't say it themselves, I can say with confidence that they'll be doing everything they can to help. It's a reputation issue - these people are a tiny minority of their users and they want the remainder to see them doing all they can to track them down.
Rim don't need to reveal the actual contents of messages in order do that. They can tell police who sent a message to whom and when. The police can then ask the network operators where that was done - and the sum total will probably be enough to be used as evidence.
If you know a Blackberry belonging to a suspect sent a message to 45 other Blackberries and then those 45 owners all turn up in Ealing or Tottenham an hour later, it's clear what's going on."
Ben Wood, mobile technology expert, BBC News website