From the letter: 'SCO believes that the GPL -- created by the Free Software Foundation to supplant current U.S. copyright laws -- is a shaky foundation on which to build a legal case.'" The release is also carried by NewsForge. Among other things, SCO says "By so strongly defending the controversial GPL, IBM is also defending a questionable licensing scheme through which it can avoid providing software indemnification for its customers."
Doesn't supplant mean "replace"? That's not what the GPL does.
And if you're wondering why you have not received an invoice from SCO for any Linux-based OS you may be running, benploni writes "From Groklaw: In this Detroit News story Blake Stowell explains why no one has received an invoice: 'SCO in August said Linux users could avoid lawsuits by paying a one-time fee of $699. The fee will rise to $1,399 on Oct. 15. Since the response to its appeal was adequate, SCO didn't send bills to thousands of Linux users, company spokesman Blake Stowell said.' [emphasis added]. We all knew there was no way they'd risk actually sending out invoices, and here's the proof."