There is no doubt that tweeter has taken off in many ways, even in overtaking Facebook's recent growth phenomenon. But what is clear, is that you really should not tweet while you're a witness in an ongoing trail.
A mistrial was declared by a judge when a witness was caught sending tweets to his colleague who was in the same courtroom. The fact that he was 'tweeting' during the break made no difference at all as a witness who in under oath must not divulge information about the subject matter while under oath and until he is released by the judge.
This is a much misunderstood rule especially by members of the public who are called as witnesses for a trial. Their lawyers will often warn them no to speak to anyone, including family members, about the case while they are still oath. The situation becomes more tricky if there is an overnight adjournment, where witnesses think that its impossible for anyone to know whether he discussed the case or not.
And that's where it goes wrong. The opening line of questioning the next day by counsel (especially of opposing counsel) will be, "Did you discuss this case with anyone last night?" and the unsuspecting witness might just let slip, not realising the seriousness of this matter.
This rule may sound outdated and unenforceable especially in a time where a mobile phone can be used as a recording device or where the witness can simply deny the allegation that he spoke with someone about the case. But there is good reason for the rule - it to ensure that the witness' evidence is not tainted or influenced by another person. But this belies the fact that most witnesses are interviewed and god-forbid, even 'coached' by lawyers before the trail.
But as shown by the case above, it does and can have consequences. The moral of the story: tweet with care.