SCO acquired certain rights to the UNIX operating system from Novell. Now SCO is suing IBM, claiming that their UNIX intellectual property was used in the AIX operating system. SCO is also threatening Linux users with the same allegation. SCO has refused to publicly produce any evidence to support their allegations, and there is widespread skepticism about SCO's claims.
It's complicated, but you can scan some past headlines by searching for keyword "sco".
Sorry HAL9000, but I really don't think that is a fair representation of what is actually going on.
First, SCO never had issue with IBM using UNIX code in AIX. Hardly, this was one of their greatest revenue points, and it was how UNIX technology was legally getting to IBM from SCO in the first place.
Second, SCO is also threatening all Linux users in general not only for whatever code IBM may have put there, but what other UNIX licensees or other former ATT programmers may have contributed as well as have been found through examination of the mailist files as well as confirmed in the source code.
Also, SCO has offered anyone the right to view samples of their evidence, and many have including Ms. Didio who recently appeared in an article on EE Times that like many we are currently seeing seemed to add validity to SCO's claims.
http://www.eetimes.com/story/OEG20030609S0011
If I could recommend one additional link in addition to those on FR where the topic is discussed at great length, that may better focus these issues I am attempting to clarify it would be this one from Byte magazine:
http://www.byte.com/documents/s=8276/byt1055784622054/0616_marshall.html
Happy reading.