Forget about Tivoization. How about adding a clause to the next version of the GPL that counters Novellization? The clause would say (in proper legalese), that if any code infringes on intellectual property or patents held by third parties, and the third parties take legal action, the contributors of the offending code assume 100% liability. In short, if Novell injects Microsoft IP into open source and Microsoft wants to sue, it must sue Novell and nobody else, because Novell assumes liability under this new license. This would render any "promise not to sue the end customer" agreement with Novell meaningless.

One might think that this would strike fear into the hearts of individual contributors. But that's not usually the way the legal system works. People and companies sue for money. Unless you're a multi-millionaire who contributes code for fun, Microsoft lawyers are smart enough to know you won't be able to pay damages. At worst, Microsoft might litigate just to create more fear. In the end, you might be forces to remove the offending code and replace it. Big deal. Unless Microsoft really wants to be perceived as the ultimate evil empire, Microsoft is unlikely to go even that far, unless you contribute a blatant rip-off of their IP.