I've always been of the opinion that competition is a good thing. It encourages all of us to be better and make better products. While it might be true that imitation is the sincerest form of flattery, copying someone else's work is simply wrong.
We recently came across a competitor using our sales copy. The competitor was using a web graph showing the traffic on one of our sites, along with our sales copy to promote their competing application. Digging a little further, I realized that their competing application was, in both form and function, identical to our application. The competing program contained identical screenshots, custom program icons and our help documentation. While the code of the program was, in fact, different, it was clear that our copyright had been violated.
We are not the first company to have our copyright violated and once the initial emotional reaction passed, we took action.