This topic includes SCO, Caldera, and TSG
A company strongly disliked by Linux advocates, The SCO Group / Caldera has a current business model based on intellectual property. It was formed from a financially unsuccessful merger between The SCO Group (TSG) and Caldera, both niche companies developing X86 software. It is currently embroiled in a multi-billion dollar lawsuit with IBM over Linux that threatens to spill over into the rest of Linux. Threats to major Linux vendors, users, and even Linus Torvalds have somehow gotten into the theater of activity.
Note about TSG confusion: Do not confuse TSG with SCO; SCO has been renamed to Tarantella and has nothing to do with the lawsuit! Although TSG has some Intellectual Property of SCO. More often than not, people do not make the distinction between oldSCO (SCO) and newSCO (TSG).
Prior to the merger, Utah-based Caldera were most known for their DR-DOS product, an MS-DOS competitor that caused them to succesfully sue Microsoft. SCO was also involved with Microsoft in earlier times - they bought the rights to continue development of Microsoft's early UNIX-workalike, Xenix, in the 1980s. Part of this deal involved Microsoft pulling out of the UNIX market for good. In 1995, SCO purchased the rights to develop UNIX from Novell (who in turn had bought it from AT&T) and developed the UnixWare operating system. The attempt to migrate their users from the Xenix-based OpenServer operating system was largely unsuccessful, and led in part to the merger with Caldera.
Many believe the current lawsuit to be a quick way out for the corporate executives. Both Caldera and SCO were fairly respectable members of the corporate and UNIX / Linux community until the recent issues with IBM. If IBM settled by buying out TSG, the executives would leave rich and happy. Unfortunately this would probably leave the employees in the dirt, not to mention the thousands of small businesses around the world that have relied on OpenServer due to its status as a cheap, X86 UNIX. On the plus side, BSD and Linux have now advanced to the point where OpenServer has become somewhat of an anachronism and no longer necessary. Still, the results of this company collapsing would be felt all over the world (see: interdependence).
TSG / Caldera's public relations method of choice is the phrase "Relax. Worry Free Software." Presumably, this is to imply that, with them, you will not get sued but, in reality, this has created a firestorm in the OS, UNIX, Linux and Free Software communities.