From what I’ve read so far, it looks like the SCO vs. IBM case comes down to SCO accusing IBM of abusing SCO trade secrets in its work on AIX and Linux. I really don’t know much about trade secrets as opposed to patents or copyright (or even trademarks), but fortunately Nolo Press came through as they always do. It seems that the fundamental issue is whether IBM employees who signed a nondisclosure agreement and were exposed to SCO’s proprietary information utilized that information in work on AIX or Linux.