The Register: In an almost comical turn of events, IBM is charging that SCO cannot claim bits of the Linux operating system are proprietary since SCO once sold a version of Linux under the GPL. IBM is also looking to secure its own IP by charging that SCO has infringed on four Big Blue patents. Last but not least, IBM claims that SCO disrupted IBM's server business by terminating its AIX license.
I'd say this is exactly what SCO's lawyers didn't want to have happen. IBM's suit makes too much sense to me. Many people pointed out that SCO licensed its supposedly proprietary code under the GPL when they were still selling Linux. Now IBM's lawyers seem to be taking action. Bye, bye SCO.