The June 2003 issue of the magazine Birdtalk has a short article called "Pigeons In The Trenches" about
the pigeons being used as sensors in the Iraq war. The article doesn't say a thing to suggest that this is a bad idea. Instead, it briefly describes the current situation, and points out that pigeons have been used in war before. The article even lists a web site that describes some of these famous military pigeons.
You'd think that a magazine that purports to be "dedicated to better care for pet birds" would say something against this practice.
Ironically, on that same page the magazine also has a brief article describing a product designed to protect pets from chemical or biological attacks. It's sort of a plastic bag with air filters and blowers. Maybe I should get some for those pigeons.