So George W. Bush and his team have gone on the offensive to defend their warrantless phone taps. What they keep telling us is that they needed to do this as part of the war on terror. That if someone is talking to Al Qaeda they want to know why.
Even if you accept that at face value because this guy never lies (except that time about WMD, and that time he said we don't use torture, and that time he said "Brownie you're doin a heckuva job", and that other time he said that we never spy on Americans without a warrant, but other than that...) it doesn't address why they need to do it without a warrant.
The FISA Court has only ever turned down four warrant applications in its entire history - there's a rubber stamp if I've ever seen one - and even has a process to apply for warrants retrospectively. So why won't the Administration come clean and tell us why it didn't follow this process rather than violating the law and the constitution? My guess is that despite their attempts to paint this as following up very specific leads, it's actually a fishing trip and wouldn't have satisfied even the rubber stamp court. But that's just a guess... maybe it's just about proving a point - that the President's power is absolute. Tyrants get hung up on stuff like that.