As someone who doesn't like reinventing the wheel when it comes to code, the code reuse implications of "work for hire" are high on my list of issues.
It is particularly applicable if you go into a project with modules that you have developed on your own. Unless you have some sort of special deal with the client, you could be handing over your own intellectual property to the client and then be prohibited from using it.
You could always make a token effort to avoid intellectual property problems by simply renaming variables and making minor mods to subroutines and objects with each client. As long as all the easily identifiable
'fingerprints' are gone, it might be looked upon as being different.
To look at another side of the issue, I sometimes wonder what would happen if someone else reused MY code in their project and I get prosecuted for violation of intellectual property laws. If you have access to source code written by someone else, it is really easy to copy stuff over and leave 'evidence' that somebody else violated IP laws.
