But to be fair gs, there have been lots of transparent docks, sliders, and theme components for the iPhone and iPad in the past... Probably more than any other type. Glasklart has had a "no dock" component on the iPhone for years I think!
It is bad is someone has just copied your theme, and worse if they used the same name, but I don't think you can really claim artist rights over a transparent png. Heck, I even changed your "no dock" theme on my own earlier in the week because I wanted to be able to see all my icons. I was going to send it to you just before I saw you fixed it yourself...
All I'm trying to say is don't get yourself too worked up if someone has copied you. It's just not worth getting yourself upset. If you had put weeks / months of work into original artwork for a theme, fair enough, but even then you know as well as I do that if you release a paid theme it will appear in half a dozen cracked repositories within 24 hours...
Just enjoy the praise you get for your work from friends like those in this forum, and channel that frustration into some new themes!