What about if you have a client that requests that the code stays secure so that competitors can not use or adapt it? Especially if the code inlcudes the use of unique business algorithms?

For example, say a small web design firm has spent the last 4 years building a web marketing business, and has developed systems to track customers, projects, sales, sales leads, etc. They now want to turn this paper system into a Intranet using Perl. But they either don't want their competitors getting the code, or want to sell the code? Wouldn't you want to protect the code source some how?

Just an example of why to protect the source, customer needs.