As we learn more about what is going on here, I have to feel that that there are some surprises, but nothing too exciting. The UK and the USA is using massive metadata collections to do social network analysis and find people. Many people are surprised by this, I am not. I am surprised however by some of the vagueness in the approval process. Whether what Snowden actually released will turn out to be a clear and present danger is unknown at this time.
Here are some references to articles about how the NSA uses the metadata, a brief discussion of how congress and the judiciary approvals in the process and my own personal opinion that the foreign policy and intelligence uses of this kind of data are so important that we will never get them to stop. The best we can do, I think, is to control what other uses the data is put to. This is a somewhat cynical opinion on my part.
I am disappointed to read that the NSA can turn over material that they inadvertently quote end quote stumble upon to the domestic agencies. I can not see why that would be a good idea; it would not be used directly in court as that surveillance was done without an explicit warrant, (if I understand the law correctly and I probably don't), but I suppose that information in that surveillance could be useful for other parts of an investigation which could be used in court. The point is that since such surveillance is done under a blanket "warrantless" procedure on metadata, it seems like a very bad idea to use that information for any domestic criminal matter. It seems to me like you are just asking to get people mad at you over their constitutional rights.
0. So far the best article I have read on the issues here is this one:
What you want to do if you want to understand this is to read about FISA and how it is has changed and what the controversies are.
But in the case of the current matter, when Pres. Obama says that "Congress and the Judiciary were informed" he is probably referring to the briefing of either the Gang of 8 or the full intelligence committees (I am not sure which) and the special court set up by FISA.
I promise you that this is all complicated and you will spend time understanding how it is supposed to work, and then how it is alleged that it does work, or, depending on who you talk to, does not work.
3. Future Direction
You will never be able to get the intelligence community to give up looking for the next Zimmerman Telegram. But it might be possible to make the fruits of surveillance less useful to the state apparatus. The simplest way is to make information gained by surveillance inadmissable as evidence in criminal or civil court. Furthermore, it would be useful to make the release of surveillance material for purposes other than national security a criminal act. If they are just sneaking around for national security purposes, then there is no need for them to be able to use the data for anything else, like violations of the criminal code. Furthermore it should be possible to sue for damages for the non-national security uses of their research. These changes in law, which may or may not be possible, would certainly reduce the harm that came from surveillance, a surveillance which I should say is probably inevitable.