I don't think there is a perfect analogy.  As Bruce said, it all depends on the relationship between the parties involved. 

I just want to clarify a few things since I know others will find this post.  The free version of Active Forums, Active Forums Lite, is the only version that includes a very small logo at the bottom.  Again, this is the FREE version.  None of the paid versions of Active Forums display a logo.  For the past four years we have always displayed the product name and version in a very small and light color font at the bottom of the page.  The latest release of Active Forums Enterprise removed the link to our site from the product name and allowed you to hide the name using CSS.    In four years, this is the first time this subject has received this much attention.  None of our other modules display any kind of branding other than product information in the module control panel.  It is very common to display the product name for forum packages.  I was just on the HP forums today and they even display the name of the forum product they are using.  Dell forums were the same way until they switched to CS (considering all the bad reviews on the forums now this is probably good for CS ).

All of the major forum packages display the product name by default.  A few charge extra if you want it removed.  Others will not let you remove it all.  We are trying to be flexible.

Thanks,

Will