I admit to being rather uninformed about what seem to be a number of important differences between v2 and v3 of the GPL. Someday I'll read the License.
I do know there are provisions to defend the "spirit" of the GPL against the adoption of patent protections for software. (Luckily for many of you here, this has no direct bearing on you since you're not living in the US.) I read the
Groklaw discussion of the Novell/Microsoft deal in light of GPLv3. PJ contends that if Microsoft agrees not to sue Novell's customers for the use of MS's patented technology, then GPLv3 would require Microsoft to extend the same guarantees to all users of the software. In essence, GPLv3 could turn the deal against Microsoft. There's a bunch of thorny legal territory to cover though. GPLv2 uses the phrase "distribute" when it defines the action covered by the license. GPLv3 uses the phrase "convey," which PJ claims has a broader reach than distribution and could include Microsoft's agreement to give away SuSE coupons.
When Microsoft cut the deal with Novell, it agreed to distribute coupons redeemable for a licensed copy of SuSE Linux Enterprise,
but they didn't specify a version or an expiration date. Thus does the redemption of one of these coupons next year for a current version of SuSE that contains GPLv3 content (Samba for sure) constitute "conveyance" and bring Microsoft under the terms of the GPLv3? If the litigation (and there'll be a lot of it) supports this perspective, the coupon deal might come to be seen as one of Microsoft's stupidest acts in recent memory. Most lawyers I know like to limit their clients' liability as much as possible, so they'd be arguing for things like specific versions or termination dates. Where were Microsoft's lawyers? Was this deal so small potatoes for Microsoft that no one really paid attention to what the consequences might be?
One problem that's been raised about moving the Linux kernel to v3 is that there are many different copyright holders in the kernel code. Some of them may have licensed their code under "version 2 or later versions," but others may have only licensed their code under GPLv2. All of these developers would need to agree to move their code under the v3 license before Linux as a whole could be licensed under GPL v3. I don't know how many such people there are, but if it's more than a handful, it could take a long time to secure their agreement. For instance, some of the drivers may not have changed much since the 1990s, and the authors of that code may be hard to track down.
Linus owns the trademark for Linux®, but he doesn't own the copyrights to the Linux code base. I don't think he has intention of exploiting his trademark to the detriment of Linux users and developers, however. My understanding is that he obtained the trademark more as a defensive measure to block some future group like SCO from owning it and calling its version "Linux®."