The NYT grammar blog had an excellent entry on this: http://opinionator.blogs.nytimes.com/2012/05/21/the-most-comma-mistakes/ http://opinionator.blogs.nytimes.c

The NYT grammar blog had an excellent entry on this: http://opinionator.blogs.nytimes.com/2012/05/21/the-most-comma-mistakes/ http://opinionator.blogs.nytimes.com/2012/05/21/the-most-com... The author, a college professor, lamented how many students still come to his class making this mistake.