Matt Asay always has thoughtful commentary on the market, and we found his opinion on the GPLv3 license interesting. There is also an interesting TalkBack to Matt's blog from Giovani Spagnolo
For what's it's worth, our research indicates that GPLv3 adoption is likely going to be tied to new releases, since it is incompatible with existing GPLv2 licenses and most other licenses. A number of the GPLv3 releases that were announced do not exist beyond a roadmap and their presence along with a license file in a CVS repository.
Therefore, the “or later” does give us an indication of a conditional adoption, the near future will start to more clearly show the signs as many of the projects that we are watching, the ones that have 2 – 4 milestone releases a year, will have their next milestone release represent the new licensing.
Based on the signs so far, we are seeing a slight increasing rate of adoption over the short time since the license has been released.