Evidently Prof. McCallum's writings (e.g. this) on nominal GDP targeting have stirred up some debate in the blogosphere...

http://newmonetarism.blogspot.de/2012/07/some-doubts-about-ngdp-targeting.html

http://www.themoneyillusion.com/?p=15157

http://economistsview.typepad.com/economistsview/2012/07/some-doubts-about-ngdp-targeting.html