We are only now learning about NSL abuses that occurred in 2006. This suggests that we won't learn about 2007 abuses until 2009, and abuses happening today won't be revealed until 2010. After-the-fact investigations and procedural reforms are no substitute for case-by-case judicial oversight. Once abuses have occurred, there isn't a lot that can be done about them. Only by having a judge review each and every national security letter—before it's issued—can we be confident that the abuses identified in recent OIG reports will not recur in the future.
National Security Letters are a way for the FBI (and presumably other government agencies) to subvert the need for a court order. Rather disturbing that these exist at all, let alone have gone rampant.