If, like me, you're trying to make sense of the recently passed FISA legislation, publius of Obsidian Wings has a much clearer description of the bill than anything I've read elsewhere.
And for even more detail, there's this and this by Marty Lederman, who notes: "The amendment means, I think, that that as far as statutory law is concerned, all of our international phone calls and e-mails can be surveilled, without exception, as long as the surveillance is in some sense 'directed at' a person overseas." If I'm reading this post by Orin Kerr correctly, it's not at all clear that the Fourth Amendment would preclude this.
--Bradford Plumer