David Friedman has an insigtful post about the nature of technological protection:
Intellectual property in digital form is easy to copy. In a networked world, it is also easy to distribute. It is therefore likely that copyright enforcement will become increasingly difficult. Tie-ins are a good solution for some forms of intellectual property but not for all. That leaves technological protection, ways of selling access to intellectual property without letting the purchaser reproduce it.
There is an important limit to such protection: It only works for forms of I.P. that are not entirely revealed in one use. However strong the encryption on the digital file containing your song, a customer can still tape record it when he plays it–or record the signals his computer is sending to its speaker, thus eliminating the sonic middleman. However well encrypted your novel, I can still, if I really want to, photograph my screen as I read it and run the pictures through OCR software.
There are other forms of I.P. that are not fully revealed in one use. What I get from Lexis or Westlaw is not a download of their database but the answer to a query. I can make a copy for a colleague but it is unlikely to be of much use to him, since he wants answers to different questions than I do. A computer program can be similarly protected, by running it on a webbed server and selling not copies but access.
I think this last point is very interesting: web-based applications like Google’s search engine don’t have much need for copyright protections, because they have a more direct way of protecting their intellectual property: it never leaves their servers. Moreover, even if an insider did steal their code, it’s complex enough that it would take quite a bit of work to set it up, and it would quickly fall behind Google’s latest version.
Similarly, Google can afford to make its map service freely available without worrying too much about someone ripping off the data because of the sheer size of the database: it would take hours (if not days or weeks) of continuous querying to get all the data, and Google can pretty easily monitor usage and cut off any user who uses too much data.
Friedman finishes his post with some interesting observations on MMORPGs like World of Warcraft as another exemplar of this technique.
(Hat tip: Mike)