By now I'm tempted to have a form-letter response ready for everyone who brings up the false rumor about the "Veggie Monster" change; it'll probably look like what I sent this guy, though I'll have to send it privately because of the web links included as proof.
The Veggie Monster scare is just an urban legend. Sesame Workshop DID have Cookie Monster cut back on his trademark food and act more concerned about his health--but he has definitely not turned into the Veggie Monster. (In fact, a recent episode had Matt Lauer interviewing Cookie, who complained that the media blew everything out of proportion.) Check out these links if you need proof--
http://muppet.wikia.com/wiki/Episode_4115
http://muppet.wikia.com/wiki/Cookie_Monster:_A_Cookie_is_a_Sometime_Food
and, from another site--
http://www.snopes.com/radiotv/tv/veggie.asp