For ten years, I've been building up a bunch of standard advice on GPL compliance. Usually, I've found myself repeating this advice on the phone, again and again, to another new GPL violator who screwed it all up, just like the last one did. In the hopes that we will not have to keep giving this advice one-at-a-time to each violator, my colleagues and I have finally gotten an opportunity to write out in detail our best advice on the subject.
Somewhere around 2004 or so, I thought that all of the GPL enforcement was going to get easier. After Peter Brown, Eben Moglen, David Turner and I had formalized FSF's GPL Compliance Lab, and Dan Ravicher and I had taught a few CLE classes to lawyers in the field, we believed that the world was getting a clue about GPL compliance. Many people did, of course, and we constantly welcome new groups of well-educated people in the commercial space who comply with the GPL correctly and who interact positively with our community.