That is over the Monterey Project. The project to move *ALL* unix vendors to this single spec, or set of Binaries fro the Itanium (whole nuther story there about Intel abandoning the whole ITANIUM project), thereby restoring a unix fracturing that happened in the 80's and 90's.
SCO is pissed, because IBM legally had the right to completely backout... SCO figgerd the IBM wouldn't do that, cause that'd be insane. Well, obviously they did backout and then SCO had a product NO COMPANY WOULD WANT. Spent about the same amount(time and money) on it IBM did, but guess that drop in a bucket for IBM was a big chunk for SCO.
That was the reason the original SCO moved to shed it's OS stuff. Now Tarantella lives on as a Canopy company as well, and SCalderaO decided to "recover costs".
Most of this(I am betting) is revenege for this fiasco called Monterey.