Rev. B iMacs

Just a couple of questions about the next round of iMacs, and I apologize in advance if the answers are common knowledge in these quarters.

1) What's the consensus as to when the Rev. B iMacs will come out? Early summer? Fall?

2) Will they likely have a speed boost in the form of a faster processor speed or it will it be a new processor? Any major changes likely to occur?

I ask as I'm considering putting my weak willpower to the test and waiting for them rather than getting the current iMac. It's not because I don't like what I hear about the current iMacs – they sound great – but more a case of not really needing a new Mac just yet. But, at the same time, I'm not sure I can stomach waiting until, say, October or latter...