If you follow open source, or at least this blog, you remember the debate around GPL and the ASP loophole. In a nutshell, companies using a trick to avoid returning changes to the code back to the community.
read more @ Funambol [1]
Links:
[1] http://www.funambol.com/blog/capo/2008/02/we-have-submitted-agpl-to-osi.html