Rerouting Internet Traffic by Attacking BGP Renesys is reporting that Internet traffic is being manipulatively rerouted, presumably for eavesdropping purposes. The attacks exploit flaws in the Border Gateway Protocol (BGP). Ars Technica has a good article explaining the details.
The odds that the NSA is not doing this sort of thing are basically zero, but I'm sure that their activities are going to be harder to discover.