Design Plagiarism

An interesting post at Design Observer got me thinking quite a bit about the idea of interaction design, graphic design (and all other aspects of HCI) and what constitutes an original idea. As fledgling interaction designers, we share ideas and use patterns and proven methodologies, and adapt existing widgets to our own purposes and liking. But where do we draw the line when we choose to "borrow" from someone else's work, especially when it is borrowed unwittingly? What about reusing code in interactive products? Copyright and intellectual property law probably have strict definitions as to what is protected, and how, but when it comes to ideas and their graphical or interactive representations, I think the lines get blurred. Can you copyright or patent a graphical layout, an interactive widget, or a page flow or process? Apparently you can: several years ago, Amazon tried (and succeeded) to patent their 1-click ordering method which raised the ire of the software community.

This makes me wonder though...how can I know if an idea I've come up with is really my own creation?