In 1985, I designed a signature chair. I had resisted the temptation to emulate designs that others had created and came up with a totally unique design that was based on a totally unique construction method.
This was my chair. The editor of a magazine I was doing a lot of work for at that time saw the chair and asked me to do a write up on it. I realized that this would be a how to and would, in essence, grant my blessing to anyone who wanted to make one. But I did not really have a problem with this since the readers were not likely to claim authorship of the design. The chair subsequently appeared on the cover of the magazine and was featured in a two-page color spread on the inside, something that was pretty unusual, at least in this particular publication, for a woodworking project.
Some years later the exact same chair appeared on the website of another well known furniture maker. It was presented as his design and there was no mention of any previous incarnation of the design. The chair is still featured on the maker's web site. A.J.'s point that "imitation is the sincerest form of flattery" may be true but this was one instance in which I would have much preferred to not be flattered.
I recently experienced a similar event in which a piece was displayed on an Internet forum that was obviously in imitation of several pieces I had posted pictures of. Again, this is a "signature" design or style that I had developed. Sure, there are elements that could be found in the work of any number of other woodworkers. But I had put a lot of thought and effort into coming up with my own distinctive style and people were starting to recognize these pieces as being made by me. What really bothered me was that there was absolutely no acknowledgment of the fact that this was an obvious imitation of my work.
There have been many times when I have borrowed from other makers. It is not at all uncommon for creative types to spin off the work of others. But it is imperative that we acknowledge the work of others. Whenever I have been inspired by something I have seen that gives me an idea, I have always tried to at least give a nod to the one who offered the inspiration. Not doing so, in my mind, is simply unethical. And if the copycat is profiting from the work of others in this manner, it could even be illegal.