Here is an interesting discussion / article on copying someones business model or even their design. Is it right to take a working site or design and re-use it or make your business around it.

Reading through this the idea behind it is that the company that is riding the coat tails, or copying another business does not know the concepts or ideas behind the final deliverable. The iterations and development that goes into the final solutions are all learning tools to make the final product.
(LINK) – http://www.37signals.com/svn/posts/1561-why-you-shouldnt-copy-us-or-anyone-else

In particular they are taking about two great business’s and sites. 37signals and Fog Creek

Original Article: (article) – http://onstartups.com/home/tabid/3339/bid/8354//Why-Your-Startup-Shouldn-t-Copy-37signals-or-Fog-Creek.aspx